顔写真

イトウ タカトシ
伊藤 高敏
Takatoshi Ito
所属
流体科学研究所 附属統合流動科学国際研究教育センター 地殻環境エネルギー研究分野
職名
教授
学位
  • 博士(工学)(東北大学)

委員歴 28

  • 日本機械学会 東北支部計算力学部門代議員

    2013年4月 ~ 継続中

  • 日本機械学会 東北支部計算力学部門代議員

    2013年4月 ~ 継続中

  • 地盤工学会 水圧破砕による初期地圧測定法の基準化検討委員会 委員長

    2012年9月 ~ 継続中

  • 地盤工学会 水圧破砕による初期地圧測定法の基準化検討委員会 委員長

    2012年9月 ~ 継続中

  • 資源素材学会 東北支部 常議員

    2012年4月 ~ 継続中

  • 資源素材学会 代議員

    2012年4月 ~ 継続中

  • 岩の力学連合会 理事

    2012年4月 ~ 継続中

  • 資源素材学会 東北支部 常議員

    2012年4月 ~ 継続中

  • 資源素材学会 代議員

    2012年4月 ~ 継続中

  • 岩の力学連合会 理事

    2012年4月 ~ 継続中

  • 岩の力学連合会 国際技術委員会 委員

    2009年8月 ~ 継続中

  • 岩の力学連合会 国際技術委員会 委員

    2009年8月 ~ 継続中

  • 土木学会岩盤動力学に関する研究小委員会 委員

    2013年10月 ~ 2015年9月

  • 土木学会岩盤動力学に関する研究小委員会 委員

    2013年10月 ~ 2015年9月

  • 深田地質研究所 岩盤応力に関する研究委員会 委員

    2012年4月 ~ 2013年3月

  • 深田地質研究所 岩盤応力に関する研究委員会 委員

    2012年4月 ~ 2013年3月

  • 金沢大学環日本海域環境研究センター 外部評価委員会 委員

    2013年1月 ~ 2013年2月

  • 金沢大学環日本海域環境研究センター 外部評価委員会 委員

    2013年1月 ~ 2013年2月

  • 第13回 岩の力学国内シンポジウム 査読委員

    2012年10月 ~ 2012年11月

  • 第13回 岩の力学国内シンポジウム 査読委員

    2012年10月 ~ 2012年11月

  • 日本地熱学会湯沢大会現地委員会 委員

    2012年5月 ~ 2012年10月

  • 日本地熱学会湯沢大会現地委員会 委員

    2012年5月 ~ 2012年10月

  • 深田地質研究所 岩盤応力に関する研究委員会 幹事

    2009年6月 ~ 2012年3月

  • 深田地質研究所 岩盤応力に関する研究委員会 幹事

    2009年6月 ~ 2012年3月

  • 日本機械学会 校閲委員

    2005年4月 ~ 2010年3月

  • 日本機械学会 校閲委員

    2005年4月 ~ 2010年3月

  • 日本地熱学会・学会賞選考委員会 委員

    2004年10月 ~ 2008年9月

  • 日本地熱学会・学会賞選考委員会 委員

    2004年10月 ~ 2008年9月

︎全件表示 ︎最初の5件までを表示

所属学協会 6

  • 米国地球物理学会(American Geophysical Union)NIA

  • 岩の力学連合会

  • 米国地熱学会(Geothermal Resources Council)

  • 日本地熱学会

  • 資源・素材学会

  • 日本機械学会

︎全件表示 ︎最初の5件までを表示

研究分野 3

  • 自然科学一般 / 固体地球科学 / 固体地球物理学

  • エネルギー / 地球資源工学、エネルギー学 /

  • ものづくり技術(機械・電気電子・化学工学) / 材料力学、機械材料 /

受賞 5

  1. 2010 Award for Research in Rock Mechanics

    2010年6月28日 American Rock Mechanics Association

  2. 岩の力学連合会賞(論文賞)

    2008年6月18日 岩の力学連合会

  3. 日本地熱学会論文賞

    2007年11月29日 日本地熱学会

  4. 日本機械学会賞 研究奨励賞

    1995年4月1日 日本機械学会

  5. (財)機器研究会 研究奨励賞

    1991年1月4日 財団法人機器研究会

論文 132

  1. On the b-value dependency of injection-induced seismicity on geomechanical parameters

    Y. Mukuhira, M.C. Fehler, E.K. Bjarkason, T. Ito, H. Asanuma

    International Journal of Rock Mechanics and Mining Sciences 174 105631-105631 2024年2月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.ijrmms.2023.105631  

    ISSN:1365-1609

  2. Analysis of large-scale performance with supercritical-water fracturing in geothermal resource development

    Bailong Liu, Anna Suzuki, Deyi Yang, Takatoshi Ito

    Geoenergy Science and Engineering 223 211575-211575 2023年4月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.geoen.2023.211575  

    ISSN:2949-8910

  3. Stress State in the Source Region of Mw2.2 Earthquake in a Deep Gold Mine in South Africa Determined from Borehole Cores

    Yasuo Yabe, Shuhei Abe, Gerhard Hofmann, Dave Roberts, Halil Yilmaz, Hiroshi Ogasawara, Takatoshi Ito, Akio Funato, Masao Nakatani, Makoto Naoi, Raymond Durrheim

    PURE AND APPLIED GEOPHYSICS 2022年4月

    出版者・発行元:SPRINGER BASEL AG

    DOI: 10.1007/s00024-022-02999-w  

    ISSN:0033-4553

    eISSN:1420-9136

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    In December 2007, an Mw2.2 earthquake occurred in a gabbroic dike at 3.3 km depth in a deep gold mine in South Africa. The fore- and aftershock activity was analyzed in an effort to understand the preparation and generation processes of earthquakes; these findings have already been published. The present paper focuses on the stress state in the source region of the mainshock. A 90-m-long borehole across the mainshock fault was drilled similar to 1.5 years after the mainshock and logged by an optical televiewer. The fault can be identified by severe damage to the borehole wall at the point where the borehole intersected the aftershock cluster. Except for a 10-m section in the hanging wall of the fault, borehole cores were fully recovered. Borehole breakout (BO) and core disking (CD) were found to occur. Two stress measurement techniques [Deformation Rate Analysis (DRA) and Diametrical Core Deformation Analysis (DCDA)] were applied to the borehole cores. By combining their results with occurrence criteria for BO and CD, the principal stress state in the source region of the mainshock was determined. The principal directions in the hanging wall of the fault were nearly identical to the virgin stress state, while it was significantly disturbed in the footwall. The vertical stresses were 106 MPa and 40 MPa in the hanging wall and footwall, respectively. The significant difference in the vertical stress between the two sides of the fault can be explained by the stress redistribution associated with a nonuniform slip on a nonplanar fault.

  4. 大深度高応力鉱山でのルーチン的な採掘ハザード定量化に資しうる岩盤コア絶対差応力DCDA測定法の試評価

    小笠原 宏, 美間 良大, 石田 亮壮, Siyanda MNGADI, 東 充也, 矢部 康男, 船戸 明雄, 伊藤 高敏, 中谷 正生, Raymond DURRHEIM

    材料 71 (3) 259-264 2022年3月15日

    出版者・発行元:公益社団法人 日本材料学会

    DOI: 10.2472/jsms.71.259  

    ISSN:0514-5163

    eISSN:1880-7488

  5. Fracturing of granite rock with supercritical water for superhot geothermal resources 査読有り

    Bailong Liu, Anna Suzuki, Noriaki Watanabe, Takuya Ishibashi, Kiyotoshi Sakaguchi, Takatoshi Ito

    Renewable Energy 184 56-67 2022年1月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.renene.2021.11.062  

    ISSN:0960-1481

  6. Flow estimation solely from image data through persistent homology analysis 査読有り

    Anna Suzuki, Miyuki Miyazawa, James M. Minto, Takeshi Tsuji, Ippei Obayashi, Yasuaki Hiraoka, Takatoshi Ito

    Scientific Reports 11 (1) 2021年12月

    出版者・発行元:Springer Science and Business Media LLC

    DOI: 10.1038/s41598-021-97222-6  

    eISSN:2045-2322

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    <title>Abstract</title>Topological data analysis is an emerging concept of data analysis for characterizing shapes. A state-of-the-art tool in topological data analysis is persistent homology, which is expected to summarize quantified topological and geometric features. Although persistent homology is useful for revealing the topological and geometric information, it is difficult to interpret the parameters of persistent homology themselves and difficult to directly relate the parameters to physical properties. In this study, we focus on connectivity and apertures of flow channels detected from persistent homology analysis. We propose a method to estimate permeability in fracture networks from parameters of persistent homology. Synthetic 3D fracture network patterns and their direct flow simulations are used for the validation. The results suggest that the persistent homology can estimate fluid flow in fracture network based on the image data. This method can easily derive the flow phenomena based on the information of the structure.

  7. Injection-Induced Seismicity Size Distribution Dependent on Shear Stress 査読有り

    Y. Mukuhira, M. C. Fehler, T. Ito, H. Asanuma, M. O. Häring

    Geophysical Research Letters 48 (8) 2021年4月

    出版者・発行元:American Geophysical Union (AGU)

    DOI: 10.1029/2020GL090934  

    ISSN:0094-8276

    eISSN:1944-8007

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    Like natural seismicity, induced seismicity caused by injection also shows a power law size distribution, and its gradient b-value is used for seismic hazard analysis. Despite the well-known result that b-value is negatively correlated with differential stress for natural earthquakes, there is no similar correlation for b-value variations because the differential stress is nearly constant for injection-induced seismicity, we thus investigate the b-value dependence on the relative shear stress acting on existing fractures, using the fault orientation and in situ stress information. The seismicity occurring along existing fractures having high shear stress has significantly lower b-values than does that associated with lower shear stress fractures. We examine the b-value dependency on slightly changing differential stress, but the relationship is not clear. The b-value for injection-induced seismicity is dependent on relative shear stress on faults, which is a novel physical explanation for the b-value variations of induced seismicity.

  8. Inferring fracture forming processes by characterizing fracture network patterns with persistent homology 査読有り

    A. Suzuki, M. Miyazawa, A. Okamoto, H. Shimizu, I. Obayashi, Y. Hiraoka, T. Tsuji, P.K. Kang, T. Ito

    Computers & Geosciences 143 104550-104550 2020年10月

    出版者・発行元:Elsevier BV

    DOI: 10.1016/j.cageo.2020.104550  

    ISSN:0098-3004

  9. Evaluation of flow paths during stimulation in an EGS reservoir using microseismic information 査読有り

    Yusuke Mukuhira, Takatoshi Ito, Hiroshi Asanuma, Markus Haring

    GEOTHERMICS 87 2020年9月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.geothermics.2020.101843  

    ISSN:0375-6505

    eISSN:1879-3576

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    Evaluation of fluid flow behavior is important for understanding various phenomena in a geothermal reservoir. Microseismic monitoring and location can be used to track pore pressure migration to some extent; however, microseismic information cannot directly provide the detail of flow behavior, such as how fluid flow occurs in the reservoir. In this study, we propose a new method to evaluate the entire flow-path system in a fractured reservoir. We first estimate the pore-pressure increase for each microseismic event based on microseismic and insitu stress information. We extend the discrete pore pressure data to a continuous distribution based on the idea of a main flow pathway and sub flow pathways. We also introduce a honeycomb-shaped flow pathway model, which consists of flow pathways and nodes. Hydraulic parameters are different between different flow pathways. To match observed pore pressures at the nodes, an optimization process is used to adjust the hydraulic parameters for each flow pathway. We get a proxy of the hydraulic conductivity distribution based on the flow pathway model, that can evaluate flow pathways and flow behavior. We apply this method to hydraulic stimulation and microseismic data from the Basel enhanced geothermal system (EGS) project. Our method successfully delineated the main permeable zone and caught the tendency of fluid flow behavior that is also indicated by other microseismic analysis. Our method can catch the qualitative behavior of fluid flow in the geothermal reservoir and can contribute to designing geothermal energy extraction systems and forecasting.

  10. Numerical analysis of different fracturing mechanisms between supercritical CO2 and water-based fracturing fluids 査読有り

    Bailong Liu, Anna Suzuki, Takatoshi Ito

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 132 2020年8月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.ijrmms.2020.104385  

    ISSN:1365-1609

    eISSN:1873-4545

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    Hydraulic fracturing using water-based fluid consumes a large amount of freshwater resources and pollutes a reservoir by substantially decreasing its matrix permeability. To address the problems caused by water-based fracturing fluids, the possibility of using SC-CO2 as a fracturing fluid was studied for its special properties (such as low viscosity, high density, and miscibility with hydrocarbons). Previous experimental studies have indicated that SC-CO2 is superior to water-based fracturing fluid in inducing complex fractures at the laboratory scale, while the mechanism of complex fractures induced by SC-CO2 remains unclear. This study develops a new numerical model to simulate the different performances of SC-CO2 fracturing and water-based fluid fracturing to determine the mechanisms of complex fractures. The numerical model couples an unsteady flow model based on the pore-scale network method and a solid model using the finite element method with cohesive zone elements. The unsteady flow model reproduces a two-phase flow considering viscous and capillary forces at the pore scale. Our simulation results show that both viscous and capillary forces contribute to the different fracturing performances between SC-CO2 and water-based fluid. The capillary force should be considered in the flow model when simulating fracturing in low matrix permeability rock.

  11. Experimental Study on Nano-/Microparticles Transport to Characterize Structures in Fractured Porous Media 査読有り

    Anna Suzuki, Junzhe Cui, Yuran Zhang, Satoshi Uehara, Kewen Li, Roland N. Horne, Takatoshi Ito

    ROCK MECHANICS AND ROCK ENGINEERING 2020年3月

    出版者・発行元:SPRINGER WIEN

    DOI: 10.1007/s00603-020-02081-8  

    ISSN:0723-2632

    eISSN:1434-453X

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    Nano- and microparticles are expected to have several functionalities, and the ability to control size and shape is an advantage of using nano-/microparticles. This study investigated a possibility that the sizes of nano-/microparticle can be used to extract new information on structures in a fractured medium. Flow experiments were conducted to observe the particle transport in a micromodel on which a single fracture and rock matrix (grain and pore space) was fabricated on a silicon wafer. Water and nano-/microparticles were injected into the micromodel, and the droplets were collected at the outlet. Tunable Resistive Pulse Sensing (TRPS) was used to measure the frequency distributions of particle diameters from each droplet at each time. The result shows that the larger particles were observed only at early time, while the smaller particles were detected at early time and also at late time. This indicates that the larger particles flow in a fracture quickly, while smaller particles migrate through both fracture and matrix over a wider range of time. Particles with different sizes transport through fractured media differently depending on the fracture structures. The tracer response of nano- and microparticles may be useful to evaluate the fracture structures and the flow properties for different flow pathways.

  12. Impact of fluid pressure on failure mode in shear zones: Numerical simulation of en-echelon tensile fracturing and transition to shear 査読有り

    Atsushi Okamoto, Kazumasa Fuse, Hiroyuki Shimizu, Takatoshi Ito

    Tectonophysics 774 2020年1月5日

    DOI: 10.1016/j.tecto.2019.228277  

    ISSN:0040-1951

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    © 2019 Elsevier B.V. En-echelon veins are a set of tensile fractures that develop during the initiation of shear zones under certain conditions, but factors that control fracture patterns remain unclear. In this study, we performed numerical simulations using the two-dimensional distinct element method to understand the influence of effective normal stress on the development of fractures during shear deformation. At low effective normal stress (10 MPa), dilation takes place at an angle of ≈40°–45° to the shear boundary, and en-echelon arrays of tensile fractures develop. In contrast, at high effective normal stress (150 MPa), en-echelon veins are not developed, but a distinct shear plane forms. A transient behavior characterizes intermediate effective normal stress (≈50 MPa): early tensile cracks are generated and then propagate to form larger brittle faults. In this case, the larger strain energy released in the later stage is due to the greater shear strength. Under crustal conditions, effective normal stress varies, due to the change in fluid pressure. Our results suggest that en-echelon veins are indicators of high fluid pressure, close to lithostatic conditions, i.e. effective normal stress close to zero, and that a transition of the failure mode from tensile to shear could occur in response to a dynamic change of fluid pressure during fracturing.

  13. Experimental verification of the dual bit coring method developed for stress measurement applicable in deep and high temperature environment

    T. Ito, A. Kumazawa, K. Tezuka, T. Yokoyama, K. Ogawa, A. Funato

    54th U.S. Rock Mechanics/Geomechanics Symposium 2020年

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    When rock is cored at depth by drilling, anisotropic expansion of the core occurs radially with the relief of anisotropic rock stresses. Based upon this phenomenon, we propose a new method to estimate magnitude and orientation of the maximum and minimum stresses S and S assuming a vertical borehole. We have verified the principle of the method by laboratory experiments, and developed a special tool for coring which records stress state in the shape of core. The tool has co-axial large and small core bits, and each one of the bits works sequentially from large to small ones. Then the core expands partially to have elliptical cross section due to stress relief but in the other part maintains circular cross section before expansion. By comparing the shape at each section, we can measure how much the core expands in all direction, and the measured amount and distribution of expansion allows us to estimate each magnitude and orientation of SHmax and Shmin. We have tested the tool in field experiments successfully. Hmax hmin

  14. First field test of the dual core-bit tool for drilling stress record cores at Kamioka mine, Japan 査読有り

    Kazuhiko Tezuka, Toshiya Yamamoto, Takatoshi Ito, Tatsuya Yokoyama, Akio Funato

    SPWLA 25th Formation Evaluation Symposium of Japan, JFES 2019 2020年

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    Copyright © SPWLA ,JFES 2019. All rights reserved. We have developed a tool to drill core samples which is recording in-situ stress information around a bottom of a borehole. When the core is cut from the bedrock, it is released from the in-situ stress and expands slightly in the radial direction. Using this principle, the in-situ stress can be determined from the elliptical shape of the core cross section (Funato & Ito, 2017). However, the difference between major and minor axes of the ellipse only provides the difference between the maximum and the minimum in-situ stress, but the magnitude of each stress component cannot be determined. This is because the core diameter d0 before expansion is unknown. To solve this problem, we proposed the coring procedure using the "Dual core-bit tool" so that the shape before expansion is retained in part of the core. That is, after digging a groove (outer groove) in the borehole bottom by the outer core-bit, cut a smaller diameter core by the inner core-bit in a same way as a normal coring. As a result, the shape before expansion remains in the upper part of the core, and the shape should expand due to stress relief in the lower part deeper than the outer groove. According to this concept, we made a prototype of the dual core-bit tools and conducted the first field test at Kamioka mine in Gifu, Japan. This paper describes the mechanism of the tool and the results of the field test.

  15. Estimating the seepage effect of SC-CO2 and water fracturing with a steady-state flow model considering capillary and viscous forces at the pore scale 査読有り

    Bailong Liu, Anna Suzuki, Takatoshi Ito

    JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING 184 2020年1月

    出版者・発行元:ELSEVIER

    DOI: 10.1016/j.petrol.2019.106483  

    ISSN:0920-4105

    eISSN:1873-4715

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    Supercritical carbon dioxide (SC-CO2) fracturing is a promising technology for unconventional energy development and carbon capture and storage. Experimental studies have shown that (SC-CO2 fracturing can form complex fracture networks and reduce crack initiation pressure, which are different results from those when fracturing with aqueous fluids. The complex fracture networks that form from SC-CO2 fracturing may be the result of strong seepage effects (i.e., low capillary and viscous forces). To understand the different injection behaviors induced by (SC-CO2 and aqueous fluids in low-permeability rocks, this study develops a new two-phase steady-state model based on the pore-scale network method. Although other models consider the viscous force, our model implements the capillary and viscous forces to reproduce the seepage effect. Because of the capillary force, the flow model is nonlinear and solved by iteratively solving matrix equations until a conservation of volumetric flux is satisfied. Simulation results show that the capillary force in a two-phase flow system in small pore spaces has consequential effects on its pressure distribution. Such factors lead to discontinuous pressure drops. This study shows that the seepage effect of (SC-CO2 is stronger than that of aqueous fluids and can largely avoid the capillary blockage that arises in oil-water systems.

  16. Introduction of natural fracture information to induced seismicity analysis 査読有り

    Y. Mukuhira, M. Ziegler, T. Ito, H. Asanuma, M.O. Häring

    Proc. YSRM2019 & REIF 2019 2019年12月

  17. In-situ stress constraints on the focal mechanisms of induced seismicity 査読有り

    Y. Mukuhira, T. Ito, M.C. Fehler, M. Naoi, H. Moriya, H. Asanuma, M. O. Häring

    Proc. ISRM2019 2019年9月

  18. [Keynote lecture] Spatial variation in stress in seismogenic zones in South African gold mines

    Ogasawara, H, A. Ishida, K. Sugimura, Y. Yabe, S. Abe, T. Ito, A. Funato, H. Kato, B. Liebenberg, G. Hofmann, L. Scheepers, R. J. Durrheim, the SATREPS, DSeis teams

    Proceedings of the 2019 Rock Dynamics Summit in Okinawa, A specialized conference of ISRM 39-44-44 2019年5月

    DOI: 10.1201/9780429327933-5  

  19. Rock stresses around active faults measured by using the high stiffness hydraulic fracturing technique, in Ö. AYDAN, T. SEIKI, K. KAMEMURA, N. IWATA, T. ITO Litvinenko (Ed.)

    Yokoyama, T, Murakami, M, Danjo, T, Ogawa, K, Lin, A, Lin, W, Ito, T

    Proceedings of 2019 Rock Dynamics Summit in Okinawa 616-621 2019年5月

  20. Rock stresses around active faults measured by using the high stiffness hydraulic fracturing technique

    T. Yokoyama, M. Murakami, T. Danjo, K. Ogawa, A. Lin, W. Lin, T. Ito

    Rock Dynamics Summit - Proceedings of the 2019 Rock Dynamics Summit, RDS 2019 638-643 2019年

    DOI: 10.1201/9780429327933-103  

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    The hydraulic fracturing technique is a method to measure the stress states in the rocks based on the change of the water pressure observed when the induced fracture in the borehole wall generated by water pressure reopens or closes. A new standard of hydraulic fracturing method in Japan will have two important observation parameters as shown below. One parameter is the water pressure P (Shut-in pressure) at the time when the tip of the fracture begins to close after shut-in operation at stopping pressurization in a test interval. The other parameter is the water pressure P (Reopening pressure) at the time when the mouth of the fracture begins to open when the test interval is re-pressurized. The new hydraulic fracturing technique highlights that a compliance of the measuring system was adequate for correctly measuring Pr. The small compliance means that the capacity of the water supply system is extremely small and the water supply system has the high stiffness. Small compliance is synonymous with high stiffness, and an ideal measuring system is required to have smaller compliance. We got an opportunity to measure the crustal stress by the hydraulic fracturing technique around Nojima fault which appeared on the surface at the 1995 Southern Hyogo Prefecture Earthquake. The hydraulic fracturing test was conducted at the foot side of Asano fault which is derived from Nojima fault. The measurement depth is about 800 m. The magnitude of the measured maximum principal stress is smaller than the overburden stress, and its principal stress direction does not match the fault movement and the direction of the compression axis is greatly deviated. Therefore, the current stress state around the fault is considered to represent the stress relaxation state after the fault activity. s r

  21. Experimental study of tip screenout fracturing by using CT scanner 査読有り

    T. Ito, H. Yoshida, K. Yamamoto, Y. Tsuchiya

    53rd U.S. Rock Mechanics/Geomechanics Symposium 2019年

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    Copyright 2019 ARMA, American Rock Mechanics Association. In hydraulic fracturing, a rapid rise in the pump pressure sometimes occurs late in the job after proppant is added in the injection fluid. One of the possible reasons is the formation of tip screenout (TSO), but it has not been verified clearly yet. In this study, we attempted to reproduce TSO in laboratory experiments. A new test vessel was developed, which allows us to do fracturing experiments in a cylindrical specimen of φ168 mm x 150 mm subjected to tri-axial compression, and observe inside the specimen in real time using the X-ray CT scanner. The experiments were carried out on conditions that a fracturing fluid was switched on the way of fluid injection to a slurry containing fine solid particles. As a result, it was clearly seen from CT images that soon after the slurry injection, the particles reached fracture tip and accumulated there with time. These results show that TSO is a really existing phenomenon, and it surely causes the rapid rise in injection pressure.

  22. Effect of capillary force on performance of shale rock fracturing 査読有り

    B. L. Liu, A. Suzuki, T. Ito

    53rd U.S. Rock Mechanics/Geomechanics Symposium 2019年

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    Copyright 2019 ARMA, American Rock Mechanics Association. Compared to conventional reservoirs, shale gas and oil reservoirs have super-low matrix permeability. Hydraulic fracturing is an effective technology to develop shale gas and oil resources. Water has been used as fracturing fluid, which is immiscible with formation fluid (i.e., oil and gas). When immiscible multiphase flow occurs in shale rock, the capillary force has large effect. Conventional fracturing simulation models for shale gas reservoirs assume that flow field is dominated only by viscous force. This assumption is unreasonable for low permeable rock because seepage effects influenced by both capillary force and viscous force. This study develops a new numerical model to simulate multiphase flow in low permeable rocks and to investigate the effects of capillary force on fracturing performance. The numerical model couples flow model and solid model. The flow model consists two parts: matrix flow model and fracture flow model. The matrix flow model based on Pore-scale Network Method (PNM) reproduced two-phase flow in matrix considering viscous forces and capillary forces. The fracture flow model based on unsteady flow model simulated unsteady flow in opened fractures. The solid model uses the Finite Element Method (FEM) with cohesive zone element. The validation was carried by comparison with analytical solution and experiment results. Then, fracturing performance of different capillary force were analyzed. The simulation results show that capillary force has significant impact on fracture geometry.

  23. ICDP DSeis Project 南アフリカ金鉱山マグニチュード2〜5.5の地震発生場の掘削に成功!?

    小笠原宏, 矢部康男, 伊藤高敏, 廣野哲朗

    J-DESCニュースレター 9 14 2018年5月

  24. A new method of stress measurement based on elastic deformation of sidewall-core with stress relief during coring 査読有り

    T. Ito, S. Fukusawa, A. Funato, T. Tamagawa, K. Tezuka

    52nd U.S. Rock Mechanics/Geomechanics Symposium 2018年

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    Copyright © 2018 ARMA, American Rock Mechanics Association. When rock is cored at depth by drilling, anisotropic expansion occurs with the relief of anisotropic rock stresses, resulting in a sinusoidal variation of core diameter with a period of 180 deg. in the core roll angle. The circumferential variation of core diameter is given theoretically as a function of rock stresses. These new findings can lead ideas to estimate the rock stress from circumferential variation of core diameter measured after the core retrieving. When several core samples with different orientation are available, all of three principal components of 3D rock stress can be estimated. If we apply an advanced technology of the rotary sidewall coring tool, we can have cores with the orientation of core axis deviated from the originally-drilled borehole axis by a right angle, 90 deg.. By using both of a sidewall core and a core of the originally-drilled borehole, we can determine absolute magnitude of 3D in-situ stress. The theoretical relationship between the core expansion and rock stress has been verified through the examination of core samples prepared in laboratory experiments and retrieved field cores.

  25. A study of the effect of brittleness on hydraulic fracture complexity using a flow-coupled discrete element method 査読有り

    Hiroyuki Shimizu, Takatoshi Ito, Tetsuya Tamagawa, Kazuhiko Tezuka

    Journal of Petroleum Science and Engineering 160 372-383 2018年1月

    DOI: 10.1016/j.petrol.2017.10.064  

    ISSN:0920-4105

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    © 2017 Elsevier B.V. In recent years, hydraulic fracturing has emerged as an important technique for the development of unconventional tight gas and oil reservoirs, particularly shale reservoirs. Production from a tight reservoir requires hydraulic creation of a highly fractured network for significantly improving the hydraulic conductivity of the reservoir. Field observations have empirically indicated that fracture complexity tends to be higher in the case of higher rock brittleness which is defined as the combination of the Young's modulus and Poisson's ratio of a rock. The brittleness is considered as one of the most important mechanical rock properties of unconventional tight reservoirs. However, the physical relationship between fracture complexity and the brittleness remains unclear. In this study, a series of hydraulic fracturing simulations were performed using a flow-coupled discrete element method to gain insights into the effect of the brittleness on fracture propagation. The brittleness was adjusted under different combinations of Young's modulus and Poisson's ratio for four rock models. Considering mechanical rock properties and pre-existing fractures, the effective stress in the case of lower brittleness reduced to the tension only around the tip of the hydraulic and pre-existing fractures. On the contrary, the tensile region was more widely distributed along the pre-existing fracture in the case of higher brittleness. The effective tensile stress in a wider region should induce more microcracks, thereby enhancing the possibility of the hydraulic fracture branching off from the pre-existing fracture. These considerations indicate a positive correlation between the brittleness and the complexity of a hydraulically induced fracture system.

  26. Hybrid focal mechanism determination: Constraining focal mechanisms of injection induced seismicity using in situ stress data 査読有り

    Y. Mukuhira, K. Fuse, M. Naoi, M. C. Fehler, H. Moriya, T. Ito, H. Asanuma, M. O. Häring

    Geophysical Journal International 215 (2) 1427-1441 2018年

    DOI: 10.1093/GJI/GGY333  

    ISSN:0956-540X

    eISSN:1365-246X

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    © The Author(s) 2018. Determining the focal mechanisms of injection induced microseismicity provides beneficial information not only for understanding the features of induced seismicity but also for characterizing the fracture system in the reservoir. However, focal mechanisms ofmicroseismicity are often not well determined with first motion information alone due to limited station coverage. We propose a new method to better constrain first motion focal mechanisms of fluid-induced seismicity by introducing in situ stress information estimated from borehole analysis and wellhead pressure. Since injection induced seismicity is dominantly caused by increases of pore pressure, we can use in situ stress magnitude/orientation information and the injection wellhead pressure to constrain the range of focal mechanisms. Then, the range of possible focal mechanisms estimated from available first motion data is constrained by superposing the range of focal mechanisms that can slip from the in situ stress condition. The use of the combined sets of information places a better constraint on focal mechanisms than can be obtained from either of the individual data sets. We apply our method to the microseismic data recorded during the hydraulic stimulation in Basel, Switzerland where the stress state is known from borehole measurements. Our method successfully constrains the range of focal mechanisms, though the degree of constraint is dependent on the distribution of possible focal mechanisms that are consistent with the first motions and the distribution that are consistent with the stress condition. We compared the range of focal mechanisms constrained by our method using data from only nearby stations with well-constrained focal mechanisms determined from first motions that are recorded by more than 50 surface stations. In the best case, 80 per cent of the focal mechanisms that are consistent with the first motion data were removed because they were inconsistent with the stress data. The constrained range of focal mechanisms includes the true focal mechanisms with significantly high probability of 0.86 even considering the uncertainty in stress information that is used for constraint. This demonstrates the ability of our method to constrain the range of focal mechanisms in situations with limited station coverage, and the benefits of introducing other geophysical data into seismological analyses.

  27. メタンハイドレート開発を目的とした未固結砂層のフラクチャリングに関する基礎研究 査読有り

    伊藤高敏, 天満則夫

    石油技術協会誌 83 (6) 491-498 2018年

  28. Status of Japanese Supercritical Geothermal Project as of FY2017 査読有り

    Asanuma,.H, Mogi, T, Tsuchiya, N, Watanabe,. N, Naganawa, S, Ogawa, Y, Fujimitsu, Y, Kajiwara, T, Osato, K, Shimada, K, Horimoto, S, Sato, T, Ito, T, Yamada, S, Watanabe, K, Gotoh, Y, Nagasawa, Y, Kohyama, A

    Geothermal Resources Council Transactions 42 2018年

  29. Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip 査読有り

    Yusuke Mukuhira, Hirokazu Moriya, Takatoshi Ito, Hiroshi Asanuma, Markus Haring

    GEOPHYSICAL RESEARCH LETTERS 44 (7) 3109-3118 2017年4月

    出版者・発行元:AMER GEOPHYSICAL UNION

    DOI: 10.1002/2017GL072809  

    ISSN:0094-8276

    eISSN:1944-8007

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    Understanding the details of pressure migration during hydraulic stimulation is important for the design of an energy extraction system and reservoir management, as well as for the mitigation of hazardous-induced seismicity. Based on microseismic and regional stress information, we estimated the pore pressure increase required to generate shear slip on an existing fracture during stimulation. Spatiotemporal analysis of pore pressure migration revealed that lower pore pressure migrates farther and faster and that higher pore pressure migrates more slowly. These phenomena can be explained by the relationship between fracture permeability and stress state criticality. Subcritical fractures experience shear slip following smaller increases of pore pressure and promote migration of pore pressure because of their enhanced permeability. The difference in migration rates between lower and higher pore pressures suggests that the optimum wellhead pressure is the one that can stimulate relatively permeable fractures, selectively. Its selection optimizes economic benefits and minimizes seismic risk.

  30. コア変形法による南アフリカ金鉱山誘発地震震源域の応力状態推定

    阿部周平, 矢部康男, 伊藤高敏, 中谷正生, Gerhard Hofmann, 小笠原宏

    第14回岩の力学国内シンポジウム講演集 (講演番号107) 1-6 2017年1月

  31. Drilling into seismogenic zones of M2.0 – M5.5 earthquakes from deep South African gold mines (DSeis): establishment of research sites 査読有り

    H. Ogasawara, R. J. Durrheim, Y. Yabe, T. Ito, G. van Aswegen, M. Grobbelaar, A. Funato, A. Ishida, H. Ogasawara, S. Mngadi, M. S.D. Manzi, M. Ziegler, A. K. Ward, G. Hofmann, P. Moyer, M. Boettcher, P. Dight, W. Ellsworth, B. Liebenberg, N. Wechsler, T. Onstott, N. Berset

    ISRM AfriRock - Rock Mechanics for Africa 2017-October 237-248 2017年

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    © 2017 International Society for Rock Mechanics. All Rights Reserved. While mining-induced earthquakes in the deep gold mines of South Africa pose a risk to mines, mineworkers, and the public, they also provide an unusual opportunity to study the physics of earthquakes. The source zone of a M5.5 earthquake that occurred near Orkney, South Africa on 5 August 2014 was well-defined by tens of thousands of aftershocks recorded by instruments deployed as part of a Japanese - South African research project. The upper edge of the M5.5 rupture is located several hundred metres below the mining horizon. A proposal to drill into the M5.5 source zone, as well as several other active faults in other deep mines, was approved by the International Continental scientific Drilling Programme (ICDP) in August 2016. Here we describe the scope and objectives of the project, and the selection and preparation of the principal drilling sites. In addition to the studies of earthquake phenomena, some of the holes will be used by geomicrobiologists to investigate deep microbiological activity fuelled by hydrogen released by seismic rupture to address questions about early life on planet Earth.

  32. Elastic deformation of core sample with stress relief by drilling and its application to rock stress estimation 査読有り

    Takatoshi Ito, Akio Funato, Tetsuya Tamagawa, Kazuhiko Tezuka

    23rd Formation Evaluation Symposium of Japan 2017 2017年

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    © 23rd Formation Evaluation Symposium of Japan 2017. All rights reserved. When a piece of rock at depth is cut out to be a core sample by drilling, it becomes free from rock stresses and expand in radial direction. The expansion occurs in an asymmetric manner with the relief of anisotropic in-situ stresses, and it results in a sinusoidal variation of core diameter with a period of 180 deg. in the circumferential direction. The circumferential variation of core diameter is given theoretically as a function of in-situ stress. These new findings can lead various ideas to determine the in-situ stress from circumferential variation of core diameter measured after the core retrieving. In the most simple case when a single core is only available, the difference between the maximum and minimum components of in-situ stress in a plane perpendicular to the drilled hole can be estimated from the maximum and minimum core diameters. If several cores with different orientation are available, all of three principal components of three dimensional in-situ stress can be determined. The technique of side-wall coring is one of possible ways to take core samples with different orientations even after a borehole has been drilled. The theoretical relationship between the core expansion and rock stress has been verified through the examination of the core prepared in laboratory experiments and retrieved field cores.

  33. Re-Opening and Shut-in Behaviors under a Large Ratio of Principal Stresses in a Hydraulic Fracturing Test 査読有り

    Tatsuya Yokoyama, Kiyotoshi Sakaguchi, Takatoshi Ito

    Procedia Engineering 191 862-868 2017年

    DOI: 10.1016/j.proeng.2017.05.254  

    eISSN:1877-7058

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    © 2017 The Authors. In-situ stress measurements were carried out under a 290m overburden in the Kamaishi mine in Iwate Prefecture of Japan. The geology of the measurement site consists of granite. The Hydraulic Fracturing (HF) technique and the Compact Conical-ended Borehole Overcoring (CCBO) technique were applied in the same horizontal borehole. The three-dimensional stress state as measured by CCBO is explained below. The directions of the maximum principal stress (σ1) and the intermediate principal stress (σ2) are almost horizontal. The direction of σ1 is perpendicular to the borehole axis, and the direction of σ2 is parallel to the borehole axis. The direction of the minimum principal stress (σ3) is approximately vertical. In this case, σ1/σ3 ratio is about 5 which is considered to be beyond the scope of the application of the HF technique. To observe the behavior of re-opening and shut-in under a large principal stress ratio, we tried to apply the HF test under these conditions. While, the re-opening pressure could not be evaluated, the shut-in pressure was observed. The results confirmed that σ3 estimated by HF is substantially equal to the vertical stress evaluated by CCBO.

  34. A new method of diametrical core deformation analysis for in-situ stress measurements 査読有り

    Akio Funato, Takatoshi Ito

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 91 112-118 2017年1月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.ijrmms.2016.11.002  

    ISSN:1365-1609

    eISSN:1873-4545

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    A new method of diametrical core deformation analysis (DCDA) is proposed for evaluating the in-situ stress of rocks from an elliptical deformation of boring cores following stress relief. When a piece of rock at depth is cut out to be a core sample by drilling, it becomes free from the in-situ stresses resulting in the expansion of its diameter. Even if the rock is homogeneous and isotropic, the core sample should expand in an asymmetric manner with the relief of anisotropic in-situ stresses. A newly developed apparatus allows us to measure the asymmetric variation of the core diameter. The difference between the maximum and minimum stress components and the stress orientations in a plane perpendicular to the drilled hole can then be estimated from the circumferential variation of the measured core diameters based upon a theoretical relationship between the in-situ stresses and the core diameters, assuming elastic deformation. We carried out laboratory experiments in which core samples were cut out from cubic specimens under uniaxial compression, and we confirmed that the stress magnitude and orientation estimated from the measured core diameters by the proposed DCDA method agreed well with those of the actually applied stress.

  35. Pore pressure behavior at the shut-in phase and causality of large induced seismicity at Basel, Switzerland 査読有り

    Y. Mukuhira, C. Dinske, H. Asanuma, T. Ito, M. O. Häring

    Journal of Geophysical Research: Solid Earth 122 (1) 411-435 2017年1月1日

    DOI: 10.1002/2016JB013338  

    ISSN:2169-9313

    eISSN:2169-9356

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    ©2016. American Geophysical Union. All Rights Reserved. Induced seismicity with unexpectedly large magnitude often occurs after shut-in or end of stimulation, generating concerns at the end of stimulation. We investigated the physical mechanism of large-magnitude induced seismicity during shut-in following the hydraulic stimulation at Basel, Switzerland. Larger postinjection events occurred at the periphery of the seismic cloud. We estimated the pore pressure required to cause shear slip using Coulomb failure criteria from stress information, geometry of the fault planes of microseismic events, and a constant coefficient of friction. Time series analysis of pore pressure distribution indicated that pore pressure migrated to the far field even after shut-in. Redistribution of pore pressure at shut-in brought sufficient pore pressure increase to induce seismicity in the peripheral region. After shut-in, the pore pressure gradient away from the well lessened and eventually pressure became uniform. These observations suggest that the higher pore pressure, which remained in the vicinity of the injection point, shifted to the farthest field. Shut-in pressure migration caused uniform pore pressure distribution at the edge of the seismic zone. Shut-in pressure destabilized a large part of the fault located at the edge of the seismic cloud, resulting in the shear slip of a large section of the fault. Meanwhile, during stimulation, only some parts of the fault entered the critical state because of the pressure gradient. The resulting shear slip on that specific part causes moderate magnitude events at most.

  36. Distribution of stress state in the Nankai subduction zone, southwest Japan and a comparison with Japan Trench 査読有り

    Weiren Lin, Timothy B. Byrne, Masataka Kinoshita, Lisa C. McNeill, Chandong Chang, Jonathan C. Lewis, Yuzuru Yamamoto, Demian M. Saffer, J. Casey Moore, Hung-Yu Wu, Takeshi Tsuji, Yasuhiro Yamada, Marianne Conin, Saneatsu Saito, Takatoshi Ito, Harold J. Tobin, Gaku Kimura, Kyuichi Kanagawa, Juichiro Ashi, Michael B. Underwood, Toshiya Kanamatsu

    TECTONOPHYSICS 692 120-130 2016年12月

    出版者・発行元:ELSEVIER

    DOI: 10.1016/j.tecto.2015.05.008  

    ISSN:0040-1951

    eISSN:1879-3266

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    To better understand the distribution of three dimensional stress states in the Nankai subduction zone, southwest Japan, we review various stress-related investigations carried out in the first and second stage expeditions of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) by the Integrated Ocean Drilling Program (IODP) and compile the stress data. Overall, the maximum principal stress sigma(l) in the shallower levels (<similar to 1 km) is vertical from near the center of forearc basin to near the trench and; the maximum horizontal stress S-Hmax (interpreted to be the intermediate principal stress sigma(2)) is generally parallel to the plate convergence vector. The exception to this generalization occurs along the shelf edge of the Nankai margin where S-Hmax, is along strike rather than parallel to the plate convergence vector. Reorientation of the principal stresses at deeper levels (e.g., >similar to 1 km below seafloor or in underlying accretionary prism) with sigma(1) becoming horizontal is also suggested at all deeper drilling sites. We also make a comparison of the stress state in the hanging wall of the frontal plate-interface between Site C0066 in the Nankai and Site C0019 in the Japan Trench subduction zone drilled after the 2011 Mw 9.0 Tohoku-Oki earthquake. In the Japan Trench, a comparison between stress state before and after the 2011 mega-earthquake shows that the stress changed from compression before the earthquake to extension after the earthquake. As a result of the comparison between the Nankai Trough and Japan Trench, a similar current stress state with trench parallel extension was recognized at both C0006 and C0019 sites. Hypothetically, this may indicate that in Nankai Trough it is still in an early stage of the interseismic cycle of a great earthquake which occurs on the decollement and propagates to the toe (around site C0006). (C) 2015 Elsevier B.V. All rights reserved.

  37. Physics-based seismic evaluation method: Evaluating possible seismic moment based on microseismic information due to fluid stimulation 査読有り

    Yusuke Mukuhira, Hiroshi Asanuma, Takatoshi Ito, Markus O. Haring

    GEOPHYSICS 81 (6) KS195-KS205 2016年11月

    出版者・発行元:SOC EXPLORATION GEOPHYSICISTS

    DOI: 10.1190/GEO2015-0648.1  

    ISSN:0016-8033

    eISSN:1942-2156

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    The forecasting and risk assessment of induced seismicity associated with fluid injection have considerable importance for subsurface energy development. We have developed a seismic evaluation method called the possible seismic moment (PoSeMo) model to assess the potential seismic moment that could be released in the future based on current seismic activity. The PoSeMo model assumes the existence of a representative parameter that can describe the seismic characteristics of a given field. This parameter is defined as the seismic moment density, which quantifies the seismic moment able to be released per rock volume. The rock volume presumed to be in critical condition because of stimulation is defined as the stimulated rock volume. The current stimulation condition for the PoSeMo model can be estimated from the product of these two parameters. The difference between the output of the PoSeMo model and the observed cumulative seismic moment corresponds to the cumulative seismic moment that could be released in the future. This value can be transformed into the possible maximum magnitude that has clear physical meaning and that can be used as feedback on the stimulation operation for seismic hazard assessment. We have applied this model to a microseismic data set from the Basel engineered geothermal system project. We have successfully estimated reasonable values for seismic moment density and stimulated rock volume. The PoSeMo model performed well, and it provided reasonable estimates of seismic moment. The maximum magnitude estimated by the PoSeMo model was almost identical to the largest event that had occurred previously. Thus, it was concluded that the PoSeMo model satisfactorily demonstrated its feasibility as a real-time seismic evaluation method, based on physical parameters derived from microseismic information.

  38. Development of the deep rock stress tester 査読有り

    Takatoshi Ito, Toshiyuki Nayuki, Kazumasa Kalo, Akio Funalo, Takashi Satoh, Yuichi Kitagawa, Harumi Kato

    ISRM International Symposium on In-Situ Rock Stress, ISRS 2016 2016-May 376-384 2016年

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    © 2016 International Society for Rock Mechanics. All rights reserved. We have proposed a new concept in which the in-situ stress state is determined by integrating the hydraulic fracturing data and the deformation of core samples. The integration leads to improve practicality and compensate disadvantages compared with the case using each data solely for the stress determination. The redundant data set allows us to determine both of the stress magnitude and orientation in multiple ways, and the validity of rasuHs can be confirmed from their consistency. In order for applying this concept to the stress measurement at deep depth, we have been developing a downhole tool of the Deep Rock Stress Tester, DRST, composed of double packers, a high pressure pump and fluid tanks. This tool must have an outer diameter smaller than the inner diameter of a drill pipe, since the tool runs on wire through the drill pipe for carrying out the in-situ test of hydraulic fracturing in a small hole drilled additionally at the bottom of a borehole. The small hole is referred to as a baby hole. Such a way seems complicated but it should minimizes a lime for tool selling overall while avoiding the risk of trouble in boreholes such as the tool gelling stuck. Upon the success to demonstrate the prototype tool in a borehole of BOO m deep with PQ size, the 2nd type one available for boreholes with HQ size was developed, and it was applied actually to the stress measurements using a borehole of 2000 m deep. As a result, we succeeded to estimate the in-situ stress from the deformation observed for the core sample of the baby hole. However, any fracture could not be induced by the pressurization tests, and this problem was considered to coma from insufficient performance of fluid pressure applied to last intervals. Considering those results, we started to develop a new tool with higher performance, and the development has been completed recently resulting in the 3rd type tool to be applicable under the environment of high pressure up to 30 MPa and high temperature up to 100 degC.

  39. Stress state analysis of a fault plane with large induced seismicity 査読有り

    Y. Mukuhira, T. Ito, H. Asanuma, M. Haring

    50th US Rock Mechanics / Geomechanics Symposium 2016 4 3287-3293 2016年

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    Copyright 2016 ARMA, American Rock Mechanics Association. Induced seismicity associated with hydraulic stimulation for the development of underground resources has been recognized as a risk factor in causing seismic hazards and is of public concern. To understand the simple physics behind induced seismicity, we analyzed the stress state of a fault plane where large seismicity was induced during hydraulic stimulation in the Cooper Basin, Australia and Basel, Switzerland. Using information regarding the stress magnitude and orientation, and the geometry of the fault plane where large events occurred, the stress state of these events was evaluated and the pore pressure necessary to cause shear slip was estimated. The fault plane of the large event in the Cooper Basin was close to being well oriented and only needed small increase in pore pressure (∼10MPa) to induce shear slip. It was also discovered that the fault plane of the largest event at Basel required a moderate increase in pore pressure of around 20 MPa to induce a seismic event. Other large events occurring at different depths needed much lower pore pressures to induce shear slip. On the fault planes at Basel where these large events occurred, large shear stress was present, suggesting causality between shear stress and event magnitude.

  40. X線CT を利用した未固結砂層の破壊と出砂の室内実験 査読有り

    松原 大樹, 伊藤 高敏, 長野 優羽

    Journal of the Japanese Association for Petroleum Technology 80 (5) 410-411 2015年9月

  41. Flow-coupled DEM modeling for hydraulic fracturing in unconsolidated sands 査読有り

    H. Shimizu, M. Shazree, T. Ito, H. Narita

    Computer Methods and Recent Advances in Geomechanics - Proceedings of the 14th Int. Conference of International Association for Computer Methods and Recent Advances in Geomechanics, IACMAG 2014 1697-1701 2015年

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    Previous researches suggest that the hydraulic fracturing in unconsolidated sand is affected by many factors. However, the formation process of the fractures in unconsolidated sands has not been sufficiently clarified. Based on this situation, an original Distinct Element Method (DEM) code corresponding to unconsolidated sands was developed, and the mechanism of the hydraulic fracturing in the unconsolidated sands was discussed by flow-coupled DEM simulation. The model in this study has the ability to form various fracture formations depending on the permeability of the model and viscosity of the fracturing fluid. The fracture growth pattern that is observed in these simulations can be classified to no fracture, cavity expansion and linear fracture. Linear fractures formation in this simulations varies depending on the fluid mobility. Short fracture, long fracture and fracture that formed in two directions can be observed in our simulations. © 2015 Taylor & Francis Group, London.

  42. Development of experimental apparatus for real-time observation of hydraulic fracture in unconsolidated sands by x-ray CT method 査読有り

    T. Ito, Y. Nagano

    49th US Rock Mechanics / Geomechanics Symposium 2015 2 1595-1603 2015年

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    Copyright 2015 ARMA, American Rock Mechanics Association. In order to clarify the characteristics of hydraulic fracture in unconsolidated sands, we have been developing laboratory experimental apparatus to observe the hydraulic fracture behavior by the X-ray CT method. The apparatus should be designed satisfying conditions such as (i) specimens have a size to be sufficiently large for the fracture growth, i.e. more than few hundreds mm, (ii) the inside of such a large specimen is visualized within a time interval to be sufficiently short compared with a time period of few hundreds seconds required for fracture initiation and growth, and (iii) the specimen is subjected to tri-axial compression for simulating subsurface conditions. Considering those requirements, we developed several types of experimental apparatus, and finally succeeded to develop an apparatus which allows us to obtain within an interval of few seconds a CT image of a longitudinal slice of the fracture along the growing direction. The results clearly show characteristic behaviors of hydraulic fracture. For example, the fracturing fluid reached the fracture tip and invaded farther into the rock matrix; therefore, a non-wetted zone did not develop at the fracture tip, in contrast to that observed in hard rocks.

  43. コア変形法(DCDA)の室内検証実験 査読有り

    船戸明雄, 伊藤高敏, 三上 央

    Journal of MMIJ 130 (12) 515-521 2014年12月

    DOI: 10.2473/journalofmmij.130.515  

  44. Comprehensive evaluation of the initial rock stress carried out as part of a 2000m all core borehole investigation 査読有り

    T. Nayuki, K. Ando, K. Onishi, N. Nishizaka, Y. Ishikawa, Y. Ohno, S. Kato, T. Ito

    ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 2215-2223 2014年

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    © 2014 by Japanese Committee for Rock Mechanics. In the field of tectonic stress measurement, it is generally acknowledged that measuring the initial stress with high accuracy is difficult. We think the best approach to evaluate the initial rock stress is to carry out tests using multiple stress measurement techniques, to organize their mutual relationship and after reviewing the results, to performing a comprehensive evaluation, rather than reaching a conclusion based on a single measurement. A hydraulic fracturing test has been carried out in-situ. Using the retrieved core, the DSCA method and a new technique that uses the Diametrical Core Deformation Analysis (DCDA) has been carried out. Furthermore, using BHTV measurements, the breakout of the borehole has been confirmed and its occurrence has been interpreted. In this study, the maximum and minimum principal stress, as well as the direction of the maximum principal stress in the horizontal plane, has been estimated based on a comprehensive evaluation of the above mentioned results. Based on the each tests and the comprehensive evaluation, the direction of the maximum principal stress in the horizontal plane is estimated to be 85 degrees, the magnitude of the maximum principal stress at 1,700m depth to be between approximately 37 and 42MPa, and the magnitude of the minimum principal stress to be between approximately 34 and 38MPa. These results are consistent with the regional stress field derived from focal mechanism analysis.

  45. Flow-coupled DEM simulation for hydraulic fracturing in pre-fractured rock 査読有り

    H. Shimizu, M. Hiyama, T. Ito, T. Tamagawa, K. Tezuka

    48th US Rock Mechanics / Geomechanics Symposium 2014 1 715-721 2014年

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    Copyright (2014) ARMA, American Rock Mechanics Association In naturally fractured shale oil and gas reservoirs, it is expected that the hydraulic fracture behavior is significantly influenced by the interaction with pre-existing natural fractures. However, the relationship between fracture behaviors and natural fractures has not been sufficiently clarified because direct observation of all the fractures or microcracks generated during the field or laboratory scale hydraulic fracturing is difficult. In this paper, a series of flow-coupled DEM simulations varying the properties of natural fracture, such as the permeability of natural fractures and the angle between created hydraulic fracture and natural fracture (approach angle), is presented. As a results, different fracture growth patterns were observed with different combination of approach angle and permeability of natural fracture. When the approach angle is high and the permeability is low, the hydraulic fracture ignores the existence of natural fracture and it propagated straight to the direction of maximum compressive principal stress. On the other hand, when the approach angle is low and the permeability is high, hydraulic fracture propagated along with a natural fracture. After that, it branched or curved to the direction of maximum principal stress.

  46. Real-time observation of hydraulic fracture growth in soft rocks under confining stress using X-ray CT 査読有り

    T. Ito, Y. Omori, Y. Nagano

    ISRM International Symposium - 8th Asian Rock Mechanics Symposium, ARMS 2014 1632-1637 2014年

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    © 2014 by Japanese Committee for Rock Mechanics. Hydraulic fracturing has been applied to enhance oil and gas production in hard rocks and in soft rocks such as unconsolidated sands. However, many uncertainties remain in the fracturing behavior of soft rocks. In this study, we present laboratory experiments in which hydraulic fracturing was conducted in unconsolidated sand specimens, and fracturing behavior was observed using X-ray computed tomography (CT). For the experiments, a test vessel was developed to hold a soft specimen in a cylindrical shape and to apply confining stress to the specimen. Part of the vessel was constructed from carbon fiber reinforced plastic to allow interrupted passage of X-rays. The test vessel is sufficiently compact for placement on the sample bed of the X-ray CT scanner. As a simulated borehole, a casing pipe was buried inside the specimen in the direction of the diameter. Pressurized fluid passed through a slit in the casing pipe and flowed into the matrix of the specimen. The pressurization initiated a planer fracture that grew axially within the specimen. X-rays were then transmitted continuously across the specimen in the axial direction, which allowed us to obtain a real-time CT image of a longitudinal slice of the fracture in the growth direction. The results clearly show characteristic behaviors of hydraulic fracture. The fracturing fluid reached the fracture tip and invaded farther into the rock matrix; therefore, a non-wetted zone did not develop at the fracture tip, in contrast to that observed in hard rocks. Such fluid invasion should affect the fracture formation mechanism in soft rocks.

  47. Laboratory study for pore water effect on hydraulically-induced fracture behavior in unconsolidated sands 査読有り

    T. Ito, H. Narita

    48th US Rock Mechanics / Geomechanics Symposium 2014 2 834-838 2014年

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    Copyright © 2014 ARMA, American Rock Mechanics Association. We developed recently a new apparatus which allows laboratory fracturing experiments under tn-axial compression up to 15 MPa with pore water pressure up to 15 MPa. Silica sands with particle size of about 125 im are used as the simulated formation matenals. In addition to the sand, some amount of kaolinite flour is mixed for adjusting permeability. The mixture is layered in a mold to form a cubical specimen of 200 x 200 x 200 mm3 with aid of a specially-designed press machine. A fracturing fluid with viscosity of 300 mPa s is injected into a specimen through a slit of a steel pipe buried in the specimen. After the tests, we excavate the specimen bit by bit and observe how the fracturing fluid has invaded into the specimen. In the present study, to examine the effect of pore water on the fracture formation, we carried out the tests for the specimens under various conditions of water saturation, pore pressure and confining stresses. Then we found that the fracturing pressure changes in proportion to the confining stress, and it is not influenced by water saturation and the initial value of pore pressure.

  48. Possibility to remedy CO<inf>2</inf> leakage from geological reservoir using CO<inf>2</inf> reactive grout 査読有り

    Takatoshi Ito, Tianfu Xu, Hidenori Tanaka, Yuhki Taniuchi, Atsushi Okamoto

    International Journal of Greenhouse Gas Control 20 310-323 2014年1月

    DOI: 10.1016/j.ijggc.2013.11.014  

    ISSN:1750-5836

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    We present here a method to reduce the medium permeability along potential leakage paths of the CO2 storage reservoir at deep depth. This method employs a grout of aqueous solution, however, the leakage paths are plugged by not the grout itself but the products of the reaction between the aqueous solution and CO2. The aqueous solution will be injected into the fractures and rocks through boreholes. The solution will have a sufficiently low viscosity for passing through even small aperture, and it will not impact formation permeability as long as the solution is left as it is. When the solution encounters dissolved CO2, a precipitation reaction will occur. As a result, the permeability will be reduced by the precipitation filling the pores and fractures in the rocks. This idea was demonstrated through laboratory experiments simulating subsurface condition at 1000m deep, i.e. 10MPa and 40°C, and using a silicate solution. In this case, the solution - CO2 reaction should produce the precipitation of amorphous silica. The results of laboratory experiments show that the present method led to a 99% permeability reduction in a glass-bead artificial rock even its initially high permeability of few darcy. Such reduction of permeability was reproduced by reactive transport simulation using TOUGHREACT. Based upon these success, the present method was applied by numerical modeling to a 2-D caprock-aquifer system under field physical and chemical conditions. Then we considered typical two scenarios to remedy CO2 leakage from a reservoir. For the first scenario, the reactive grout of the silica solution is injected after the occurrence of CO2 leakage, and for the second scenario, the aquifer overlying the caprock has been filled with the reactive grout in advance of the occurrence of CO2 leakage. For both the scenarios, the silica precipitation were produced and they filled up pores around outlet of the leakage path so sufficiently that the CO2 migration was blocked, and the condition was confirmed stable over a long time. © 2013 Elsevier Ltd.

  49. The Japan beyond-brittle project 査読有り

    H. Muraoka, H. Asanuma, N. Tsuchiya, T. Ito, T. Mogi, H. Ito

    Scientific Drilling 17 (17) 51-59 2014年

    DOI: 10.5194/sd-17-51-2014  

    ISSN:1816-8957

    eISSN:1816-3459

  50. Numerical thermo-elastic simulation for change in fracture aperture associated with cold fluid injection 査読有り

    Kosuke Kaneta, Yusuke Mukuhira, Takatoshi Ito

    Transactions - Geothermal Resources Council 38 301-304 2014年

    ISSN:0193-5933

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    Copyright © (2014) by the Geothermal Resources Council All right reserved. We analyzed the effect of thermal contraction of rock on fracture permeability. The analysis was carried out by using a 2D FEM code which can treat the coupled problem of fluid flow in fractures, elastic and thermal deformation of rock and heat transfer. We assumed a single fracture in a high-temperature rock mass subjected to a uniform confining stresses. Under the conditions, low-temperature fluid was injected into the fracture. The results of simulation showed that even under confining environment, the considerable increase in fracture permeability appeared due to thermal deformation of rock, which should be caused by the difference between the initial temperature of rock and the fluid temperature. However, for the increase of fracture permeability, the temperature difference was necessary to be larger than a critical value, and the critical value increased with the magnitude of confining stress.

  51. 岩盤応力評価のためのユア変形法(DCDA)

    船戸 明雄, 伊藤 高敏

    Journal of MMIJ : journal of the Mining and Materials Processing Institute of Japan 129 (8) 577-584 2013年8月1日

    出版者・発行元:The Mining and Materials Processing Institute of Japan

    DOI: 10.2473/journalofmmij.129.577  

    ISSN:1881-6118

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    DCDA is a new method for evaluating the in-situ stress of rocks based on the elliptical deformation of boring cores with stress relief. When a rock core sample is carved out by drilling, it becomes free from in-situ stress, and the expansion should occur elastically. If the condition of in-situ stress is anisotropic, the core must deform in an asymmetric manner. With the precise measurement of core diameters in each directions, the deviatoric stress <i>S</i><i><sub>H</sub></i><sub>max </sub><tt>-</tt><i>S</i><i><sub>h</sub></i><sub>min</sub> and azimuths of <i>S</i><i><sub>H</sub></i><sub>max</sub> and <i>S</i><i><sub>h</sub></i><sub>min</sub> could be determined from the circumferential variation of the measured diameter. In order to confirm the reliability of DCDA, laboratory verifications were conducted. The estimated stresses by DCDA agreed well with the applied stresses, and the directions of <i>d</i><sub>max</sub> coincide to the directions of the applied stresses. From these results, the effectiveness of DCDA was confirmed.

  52. In situ stress and pore pressure in the kumano forearc basin, offshore SW Honshu from downhole measurements during riser drilling 査読有り

    D. M. Saffer, P. B. Flemings, D. Boutt, M. L. Doan, T. Ito, L. McNeill, T. Byrne, M. Conin, W. Lin, Y. Kano, E. Araki, N. Eguchi, S. Toczko

    Geochemistry, Geophysics, Geosystems 14 (5) 1454-1470 2013年5月1日

    DOI: 10.1002/ggge.20051  

    eISSN:1525-2027

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    In situ stress and pore pressure are key parameters governing rock deformation, yet direct measurements of these quantities are rare. During Integrated Ocean Drilling Program (IODP) Expedition #319, we drilled through a forearc basin at the Nankai subduction zone and into the underlying accretionary prism. We used the Modular Formation Dynamics Tester tool (MDT) for the first time in IODP to measure in situ minimum stress, pore pressure, and permeability at 11 depths between 729.9 and 1533.9 mbsf. Leak-off testing at 708.6 mbsf conducted as part of drilling operations provided a second measurement of minimum stress. The MDT campaign included nine single-probe (SP) tests to measure permeability and in situ pore pressure and two dual-packer (DP) tests to measure minimum principal stress. Permeabilities defined from the SP tests range from 6.53 × 10<sup>-17</sup> to 4.23 × 10<sup>-14</sup> m <sup>2</sup>. Pore fluid pressures are near hydrostatic throughout the section despite rapid sedimentation. This is consistent with the measured hydraulic diffusivity of the sediments and suggests that the forearc basin should not trap overpressures within the upper plate of the subduction zone. Minimum principal stresses are consistently lower than the vertical stress. We estimate the maximum horizontal stress from wellbore failures at the leak-off test and shallow MDT DP test depths. The results indicate a normal or strike-slip stress regime, consistent with the observation of abundant active normal faults in the seaward-most part of the basin, and a general decrease in fault activity in the vicinity of Site C0009. © 2013. American Geophysical Union. All Rights Reserved.

  53. ボアホールブレイクアウトに対する中間主応力の影響の実験的検討 査読有り

    青柳和平, 石田 毅, 村田澄彦, 山本晃司, 関根孝太郎, 伊藤高敏, 陳 渠

    Journal of MMIJ 129 (4) 107-115 2013年4月

    出版者・発行元:The Mining and Materials Processing Institute of Japan

    DOI: 10.2473/journalofmmij.129.107  

    ISSN:1881-6118

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    Borehole breakout, which is shear failure of the borehole wall, is one of the serious problems in drilling wells for oil/gas exploration and production. Investigation of stress condition causing breakout helps to avoid this problem. Conventionally, simple failure criteria, such as Mohr-Coulomb, which disregard the effect of the intermediate principal stress, were used to evaluate the stress condition. However, many researchers have reported that the intermediate principal stress affects the stress condition causing breakout. In this paper, the authors conducted true triaxial experiments using cubic rock specimens with a borehole to investigate the effect of the intermediate principal stress. In these experiments, measurements of tangential strains around the borehole wall and a weight of failed rock fragments by the scale, and observation of the wall using video camera were conducted to detect the failure development process. The effect of the intermediate principal stress was evaluated in five points along failure development detected by the measurements and the observations described above. The experimental results elucidated that the magnitudes of stress causing breakout clearly increase with increase of the intermediate principal stress in the all points along the failure development. However, when the authors compared the results with the three failure criteria, Modified-Lade, Drucker-Prager and Mogi, which consider the effect of the intermediate principal stress, the three failure criteria underestimated the stress condition causing breakout.

  54. Determination of Stress State in Deep Subsea Formation by Combination of Hydraulic Fracturing In-situ Test and Core Analysis – A Case Study in the IODP Expedition 319– 査読有り

    Ito, T, Funato, A, Lin, W, Doan, M.-L, Boutt, D.F, Kano, Y, Ito, H, Saffer, D, McNeil, L.C, Byrne, T, Moe, K.-T

    Journal of Geophysical Research 118 (3) 1203-1215 2013年3月

    出版者・発行元:None

    DOI: 10.1002/jgrb.50086  

    ISSN:2169-9313

    eISSN:2169-9356

  55. 海底浅部地層を模擬した試験片によるフラクチャリング室内実験 査読有り

    伊藤高敏, 大森康雅, 成田英夫

    第13回岩の力学国内シンポジウム講演論文集 1 371-375 2013年1月

  56. Distinct Element Analysis for Hydraulic Fracturing in Shale –Effect of Brittleness on the Fracture Propagation - 査読有り

    Hiyama, M, Shimizu, H, Ito, T, Tamagawa, T, Tezuka, K

    Proc. of the 47th US Rock Mechanics / Geomechanics Symp. 2 1405-1412 2013年

  57. Experimental study of hydraulic fracturing in unconsolidated sands using X-ray CT method 査読有り

    Y. Omori, S. Jin, T. Ito, Y. Nagano, K. Sekine

    47th US Rock Mechanics / Geomechanics Symposium 2013 3 1974-1980 2013年

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    Hydraulic fracturing is applied for oil and gas production enhancement not only to hard rocks but also to soft rocks such as unconsolidated sands. In the latter case, fracturing behavior is not suitably represented by existing models for brittle, linear-elastic rocks. Thus we developed an apparatus for carrying out hydraulic fracturing experiment in a cylindrical specimen under triaxial compression and tried to observe the dynamic behavior of hydraulically-induced fracture in unconsolidated sands by using a x-ray CT scanner. In those CT images, we could detect clearly how the fracture propagated and then the fracturing fluid infiltrated around the fracture. As a result, we found that the shapes of the infiltrated regions changed obviously for two cases when the fracture was and was not induced, while there was a small difference in the peak pressure of fracturing fluid. Those phenomena indicate that permeability of the specimen play an important role rather than fluid pressure on fracture formation. Copyright 2013 ARMA, American Rock Mechanics Association.

  58. Operational review of the first wireline in situ stress test in scientific ocean drilling 査読有り

    Moe Kyaw Thu, Takatoshi Ito, Weiren Lin, Mai Linh Doan, David Boutt, Yoshihisa Kawamura, Chee Kin Khong, Lisa McNeill, Timothy Byrne, Demian Saffer, Eiichiro Araki, Nobu Eguchi, Ikuo Sawada, Peter Flemings, Yasuyuki Kano, Casey Moore, Masataka Kinoshita, Harold Tobin

    Scientific Drilling (13) 35-39 2012年4月

    DOI: 10.2204/iodp.sd.13.06.2011  

    ISSN:1816-8957

    eISSN:1816-3459

  59. Scale dependence of in-situ permeability measurements in the Nankai accretionary prism: The role of fractures 査読有り

    David F. Boutt, Demian Saffer, Mai-Linh Doan, Weiren Lin, Takatoshi Ito, Yasuyuki Kano, Peter Flemings, Lisa C. McNeill, Timothy Byrne, Nicholas W. Hayman, Kyaw Thu Moe

    GEOPHYSICAL RESEARCH LETTERS 39 (7) 2012年4月

    出版者・発行元:AMER GEOPHYSICAL UNION

    DOI: 10.1029/2012GL051216  

    ISSN:0094-8276

    eISSN:1944-8007

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    Modeling studies suggest that fluid permeability is an important control on the maintenance and distribution of pore fluid pressures at subduction zones generated through tectonic loading. Yet, to date, few data are available to constrain permeability of these materials, at appropriate scales. During IODP Expedition 319, downhole measurements of permeability within the uppermost accretionary wedge offshore SW Japan were made using a dual-packer device to isolate 1 m sections of borehole at a depth of 1500 m below sea floor. Analyses of pressure transients using numerical models suggest a range of in-situ fluid permeabilities (5E-15-9E-17 m(2)). These values are significantly higher than those measured on core samples (2E-19 m(2)). Borehole imagery and cores suggests the presence of multiple open fractures at this depth of measurement. These observations suggest that open permeable natural fractures at modest fracture densities could be important contributors to overall prism permeability structure at these scales. Citation: Boutt, D. F., et al. (2012), Scale dependence of in-situ permeability measurements in the Nankai accretionary prism: The role of fractures, Geophys. Res. Lett., 39, L07302, doi:10.1029/2012GL051216.

  60. Stress State at the Expedition 319 Drilling Site Estimated from Hydrofracturing Data and Core Deformation Taking account of the System Compliance Effect

    T. Ito, A. Funato, H. Ito

    Abstract Book for International Conference on a New Perspective of Great Earthquake along Subduction Zone 2012年2月28日

  61. A new laboratory test for shear fracture formation and its permeability measurement 査読有り

    T. Ito, T. Shono, K. Sekine, K. Yamamoto

    Harmonising Rock Engineering and the Environment - Proceedings of the 12th ISRM International Congress on Rock Mechanics 645-648 2012年

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    We propose a new testing method which allows us to create a single shear fracture and measure its permeability sequentially under confining pressure, once a specimen is set to an apparatus. Then the shear sliding of fracture occurs while keeping contact of the fracture surfaces, as expected to occur in subsurface rocks subjected to compressive stresses. We constructed the apparatus and applied it to the tests using Kimachi sandstone as a rock sample. Results show that permeability of the rock increased with existence of a shear fracture, however the increment was not so significant compared with the original permeability and there was no clear correlation between the permeability increment and shear displacements of the fracture surfaces. © 2012 Taylor & Francis Group, London.

  62. Laboratory verification of the Diametrical Core Deformation Analysis (DCDA) developed for in-situ stress measurements 査読有り

    Akio Funato, Takatoshi Ito, Taito Shono

    46th US Rock Mechanics / Geomechanics Symposium 2012 2 1407-1412 2012年

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    DCDA is a new method for evaluating the in-situ stress of rocks based on the elliptical deformation of boring cores with stress relief. When a rock core sample is carved out by drilling, it becomes free from in-situ stress, and the expansion should occur elastically. If the condition of in-situ stress is anisotropic, the core must deform in an asymmetric manner. With the precise measurement of core diameters in each directions, the deviatoric stress S Hmax-Shmin and azimuths of SHmax and S min could be determined from the circumferential variation of the measured diameter. In order to confirm the reliability of DCDA, laboratory verifications were conducted. The estimated stresses by DCDA agreed well with the applied stresses, and the directions of rfmaxcoincide to the directions of the applied stresses. From these results, the effectiveness of DCDA was confirmed. Copyright 2012 ARMA, American Rock Mechanics Association.

  63. The distinct element analysis for hydraulic fracturing in unconsolidated sand considering fluid viscosity 査読有り

    Hiroyuki Shimizu, Sumihiko Murata, Takatoshi Ito, Tsuyoshi Ishida

    ISRM Regional Symposium - 7th Asian Rock Mechanics Symposium, ARMS 2012 806-813 2012年

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    © 2012 International Society for Rock Mechanics. All rights reserved. A new DEM code corresponding to unconsolidated sand was developed. The flow-coupled DEM simulations for the hydraulic fracturing in unconsolidated sand were performed to reveal the factor that significantly affects the peculiar hydraulic fracturing behavior. Especially, this research focused on the effect viscosity of fracturing fluid. As a result, the two different fracture growth patterns observed in the hydraulic fracturing experiment were successfully represented with different viscosity of fracturing fluid. When the viscosity of the fracturing fluid is 100 mPas or more, the fracture growth pattern of the Linear Fracture was observed. On the other hand, when the viscosity of the fracturing fluid is lower than 100 mPas, the fracture growth pattern became the Branched Fracture. These results indicate that the viscosity of the fracturing fluid have a large influence on the fracture growth process in unconsolidated sand. Moreover, these results suggest that the DEM model may be more appropriate for the analysis of fracturing of unconsolidated materials than the other numerical analysis techniques.

  64. Challenges to stress measurements in deep and/or unconsolidated rock formations for frontier rock engineering 査読有り

    Takatoshi Ito

    ISRM Regional Symposium - 7th Asian Rock Mechanics Symposium, ARMS 2012 19-25 2012年

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    © 2012 International Society for Rock Mechanics. All rights reserved. In these days, advanced rock and petroleum engineering tend to target deeper and/or unconsolidated oil and gas formations. Rock stress and its effect on the mechanical behavior of rock masses in such formations have drawn much attention accordingly. Taking account of such situation, we are developing new methods based upon hydraulic fracturing, which allow us to measure in-situ stress at few km deep and in unconsolidated formations respectively. In the method proposed for the deep stress measurements, the test tool is conveyed within a drill string. This way should contribute greatly to avoiding the risk of trouble occurring in boreholes such as the tool getting stuck. On the other hand, for the stress measurements in unconsolidated formations, we examined the behaviors of hydraulically-induced fractures by laboratory experiments using unconsolidated specimens made of sand and kaolin. The results show that the step rate test is effective to detect the shut-in pressure indicating normal stress across a fracture rather than the analysis of the pressure decay curve after shut-in.

  65. Effect of anisotropic confining stresses on hydraulically-induced fracture propagation from perforated cased-hole in unconsolidated sands 査読有り

    T. Ito, K. Yamamoto, S. Nagakubo

    45th US Rock Mechanics / Geomechanics Symposium 2011年

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    In order to clarify the mechanisms of hydraulic fracturing in unconsolidated formation, we carried out laboratory tests in this study. For a simulated borehole, a casing pipe was buried vertically in a cubical specimen of unconsolidated sands with moderate permeability of 5 mD. After the specimen was subjected to anisotropic triaxial compressive stresses of a few MPa, a fracturing fluid of a viscous machine oil injected into the casing pipe, and it came out through an axial slit of the casing pipe into sands. After the test, the specimens were cut off bit by bit in order to check fracture formation and invasion of the fracturing fluid. Then we observed that fractures were induced actually and the fracture pattern obviously changed with azimuthal orientation of the slit relative to azimuth of the maximum horizontal stress. A single, double or multiple fractures were induced by combination of the slit orientation and a manner of pressurization. It is inferred from the elasto-plastic FEM analysis that such fracture patterns were caused by variation of stress state around the casing pipe due to sliding of pre-induced fractures and yielding. Those result suggest the possibility to control not only length and volume but also patterns of the fractures hydraulically induced in unconsolidated formation. © 2011 ARMA, American Rock Mechanics Association.

  66. 未固結砂層のフラクチャリング挙動を模擬する室内実験 査読有り

    伊藤高敏, 五十嵐哲, 山本晃司

    Journal of MMIJ 127 (6,7) 243-248 2011年

    出版者・発行元:The Mining and Materials Processing Institute of Japan

    DOI: 10.2473/journalofmmij.127.243  

    ISSN:1881-6118

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    In order to clarify fracture initiation and propagation in unconsolidated sand, we carried out hydraulic fracturing tests in laboratory focusing on moderate-permeability sand. Silica sand with particle size of about 100 μm has been generally used as the simulated formation materials in laboratory fracturing experiments. Permeability of such sand is high in the order of few darcy. Thus we mixed finer particles of kaolinite with sand, and finally succeeded to prepare the mixture of sand and kaolinite with permeability of about 5 mD. We layered the mixture in a mold to form a cubical specimen of 200 x 200 x 200 mm<SUP>3</SUP>. At fracturing tests, the specimen was set in a loading frame of a newly-developed test system. Tri-axial compressive stresses of 2∼3 MPa were applied to the specimen. Fracturing fluid of a machine oil with viscosity of 300 cP was pumped by a constant rate of 10∼100 mL / min into a simulated borehole of a steel pipe which was buried vertically in the specimen, and then the fluid flew out inside the specimen passing through the slit of the steel pipe. After the tests, we excavated the specimen bit by bit and observed how the fracturing fluid invaded into the specimen. <BR>The laboratory tests demonstrated that fracture-like parting / fracture formation at macro scale was induced in the specimen by fluid injection. During fracture propagation, the pore pressure in the vicinity ahead of fracture tip seemed to increase due to fluid invasion. Fracture patters were obviously changed with injection flow rate. Lower injection flow rate led to a single and straight fracture and higher injection rate led to branching fractures, while in all cases, overall alignment of fractures was in the direction of the maximum horizontal compressive stress. Such phenomena are different from those observed in competent rocks.

  67. Present-day principal horizontal stress orientations in the Kumano forearc basin of the southwest Japan subduction zone determined from IODP NanTroSEIZE drilling Site C0009 査読有り

    Weiren Lin, Mai-Linh Doan, J. Casey Moore, Lisa McNeill, Timothy B. Byrne, Takatoshi Ito, Demian Saffer, Marianne Conin, Masataka Kinoshita, Yoshinori Sanada, Kyaw Thu Moe, Eiichiro Araki, Harold Tobin, David Boutt, Yasuyuki Kano, Nicholas W. Hayman, Peter Flemings, Gary J. Huftile, Deniz Cukur, Christophe Buret, Anja M. Schleicher, Natalia Efimenko, Kuniyo Kawabata, David M. Buchs, Shijun Jiang, Koji Kameo, Keika Horiguchi, Thomas Wiersberg, Achim Kopf, Kazuya Kitada, Nobuhisa Eguchi, Sean Toczko, Kyoma Takahashi, Yukari Kido

    GEOPHYSICAL RESEARCH LETTERS 37 (L13303) 2010年7月

    出版者・発行元:AMER GEOPHYSICAL UNION

    DOI: 10.1029/2010GL043158  

    ISSN:0094-8276

    eISSN:1944-8007

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    A 1.6 km riser borehole was drilled at site C0009 of the NanTroSEIZE, in the center of the Kumano forearc basin, as a landward extension of previous drilling in the southwest Japan Nankai subduction zone. We determined principal horizontal stress orientations from analyses of borehole breakouts and drilling-induced tensile fractures by using wireline logging formation microresistivity images and caliper data. The maximum horizontal stress orientation at C0009 is approximately parallel to the convergence vector between the Philippine Sea plate and Japan, showing a slight difference with the stress orientation which is perpendicular to the plate boundary at previous NanTroSEIZE sites C0001, C0004 and C0006 but orthogonal to the stress orientation at site C0002, which is also in the Kumano forearc basin. These data show that horizontal stress orientations are not uniform in the forearc basin within the surveyed depth range and suggest that oblique plate motion is being partitioned into strike-slip and thrusting. In addition, the stress orientations at site C0009 rotate clockwise from basin sediments into the underlying accretionary prism. Citation: Lin, W., et al. (2010), Present-day principal horizontal stress orientations in the Kumano forearc basin of the southwest Japan subduction zone determined from IODP NanTroSEIZE drilling Site C0009, Geophys. Res. Lett., 37, L13303, doi:10.1029/2010GL043158.

  68. Proposed Concept of In-situ Reaction Barrier to Remedy Leakage from Reservoirs of Geological CO2 Storage 招待有り

    T.Ito

    Proc. of the 2nd International Symposium of Experimental-Integrated Computational Chemistry on Multiscale Fluidics 1 55-56 2010年2月24日

  69. Dynamic monitoring of fracture extension in unconsolidated sand specimen by GPR 査読有り

    Dong Hun Kim, Motoyuki Sato, Takatoshi Ito

    Proceedings of the 13th Internarional Conference on Ground Penetrating Radar, GPR 2010 2010年

    DOI: 10.1109/ICGPR.2010.5550158  

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    We conducted a GPR monitoring to observe the extension of fractures created by hydraulic fracturing. To achieve this monitoring, a measurement system with higher time accuracy and faster data acquisition rate are needed. We designed a VNA (Vector Network Analyzer) measurement system using a Vivaldi array antenna. The VNA measurement system has the time resolution of 1 ps/sample and the data acquisition rate of 0.78 sec/acquisition, where the system dynamic range is about 100 dB. The Vivaldi array antenna has a wide frequency bandwidth of 0.3 MHz∼6 GHz. Comparing the actual formation of the fracture and the infiltrated region with the measurement result, we can verify the extension of the fracture indirectly. Also it may be possible to understand the relation between the pressure of the fracturing fluid and the formation of the fracture in real time. © 2009 IEEE.

  70. Deep rock stress measurement by hydraulic fracturing method taking account of system compliance effect 査読有り

    T. Ito, T. Satoh, H. Kato

    Rock Stress and Earthquakes - Proceedings of the 5th International Symposium on In-Situ Rock Stress 1 43-49 2010年

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    For the effective measurement of the reopening pressure in hydraulic fracturing, it is necessary to use the testing equipment with sufficiently small compliance. If not, there is no way to estimate the maximum stress in a plane perpendicular to a borehole, i.e. the maximum horizontal stress assuming a vertical borehole, from the reopening pressure. It may be very hard to reduce the system compliance drastically by just replacing any components of the hydraulic fracturing system. If the flow meter is emplaced as close as possible to a test section of a borehole isolated by straddle packers, the system compliance can be reduced drastically. To accomplish this idea, we have been developing a testing system with a downhole flow meter.We demonstrated the developed system in a field test successfully. Furthermore, we presented a new method which will allow us to do stress measurement at depths greater than a few km. © 2010 Taylor & Francis Group, London.

  71. Laboratory Test of Hydraulic Fracturing in Unconsolidated Deformable Rocks 査読有り

    T. Ito, A. Igarashi, K. Yamamoto

    PORO-MECHANICS IV 1001-+ 2009年

    出版者・発行元:DESTECH PUBLICATIONS, INC

    詳細を見る 詳細を閉じる

    Nowadays hydraulic fracturing is performed for not only competent rocks but also unconsolidated sand. In the latter case, pore pressure should play a key role on fracture initiation and propagation, while the role is still unclear. Thus we examined the fracturing phenomena in laboratory experiments, and observed peculiar phenomena such as the drastic change in fracture patterns by injection flow rate and the fracturing suppression caused by slight change in formation permeability.

  72. Effect of pore pressure gradient on fracture initiation in fluid saturated porous media: Rock 招待有り 査読有り

    Takatoshi Ito

    ENGINEERING FRACTURE MECHANICS 75 (7) 1753-1762 2008年5月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.engfracmech.2007.03.028  

    ISSN:0013-7944

    詳細を見る 詳細を閉じる

    There are infinite number of small pores at inside of almost rocks, while the pore's shape and the interconnectivity among the pores are dependent on the type of rocks. The existence of such pores brings special feature in mechanical behavior of rocks, different to cases of other materials. For the case when the pressure in a drilled borehole is raised by fluid injection into the borehole in hydraulic fracturing carried out for rock stress measurements, the fluid penetrates through the interconnected pores into a rock from the borehole wall, and the fluid penetration develops the change in pore pressure, i.e., fluid pressure in the pore. The developed pore pressure distribution causes a circumferential stress in compression around the borehole, where the mechanics to cause the additional stress is analogous to thermal stress. Furthermore, the pore pressure affects to loose strength in failure following the Terzaghi effective stress law. The point stress criterion can be applied to predict tensile failure of rock occurring in such complicated conditions. Then we should assume that the fracture initiation occurs when the maximum effective stress reaches the tensile strength of a rock at a point that is not on the borehole wall but is inside the rock. This approach allows us to interpret quantitatively strange phenomena associated with fluid permeation such that breakdown pressure, i.e., a critical borehole pressure to cause the tensile failure, increases with the rate of borehole pressurization. (c) 2007 Elsevier Ltd. All rights reserved.

  73. Numerical simulation of supercritical CO2 injection into subsurface rock masses 査読有り

    Kenta Sasaki, Takashi Fujii, Yuichi Nilbori, Takatoshi Ito, Toshiyuki Hashida

    ENERGY CONVERSION AND MANAGEMENT 49 (1) 54-61 2008年1月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/j.enconman.2007.05.015  

    ISSN:0196-8904

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    Carbon dioxide (CO2) is considered to be one of the greenhouse gases that may contribute most to global warming on the earth. Disposal of CO2 from stationary sources into subsurface structures has been suggested as a possible means for reducing CO2 emissions into the atmosphere. However, much remains to be done in the issues regarding the safety and reliability of CO2 geological sequestration. In this study, we have developed a simulation code by using the mathematical model of two phase flow in porous media to analyze the flow dynamics in the subsurface. The equation of state for CO2 covering the fluid region from the triple point to the supercritical region is employed to model the states of CO2 gas, liquid and supercritical state. The correct understanding of the CO2 state under the geological formation condition is an important factor to predict the injection pressure and CO2 fluid permeation because the fluid density has a great effect on the injection behavior. The numerical simulation was implemented under several geological conditions including gas, liquid and supercritical states to examine the optimal injection condition. Comparing the numerical results obtained using the equation of state for CO2 with those obtained using the ideal gas equation, it has been shown that the difference in the injection pressure appears to be significant near the condition of the critical point of CO2 and the phase equilibrium curves between the gas and liquid states. The numerical simulation has been implemented to examine the effect of the reservoir condition on the injection behavior. The injection pressure is decreased at the lower reservoir temperature and higher hydrostatic pressure condition. The CO2 permeation is also strongly affected by the reservoir condition, and the spatial CO2 saturation becomes higher with increasing reservoir temperature. It has been demonstrated that the simulation code developed in this study may be useful to provide knowledge required to select the reservoir condition for CO2 geological sequestration. (c) 2007 Elsevier Ltd. All rights reserved.

  74. 微小地震情報から求めた間隙水圧分布に基づく貯留層内の流路構造評価 査読有り

    伊藤高敏, 長田和義, 林 一夫

    日本地熱学会誌 30 (1) 49-60 2008年

    DOI: 10.11367/grsj1979.30.49  

    ISSN:1883-5775 0388-6735

  75. 地熱型再生可能エネルギー利用の実用化研究 招待有り 査読有り

    伊藤高敏, 新堀雄一

    伝熱 46 (196) 28-37 2007年7月

  76. High-resolution aftershock observations in the source region of the 2004 mid-Niigata Prefecture Earthquake 査読有り

    Aitaro Kato, Masakatsu Arao, Keisuke Ariyoshi, Youichi Asano, Keiji Doi, Bogdan Enescu, Shinya Fujieda, Hiroko Hagiwara, Toshio Haneda, Akira Hasegawa, Shin'ichi Hashimoto, Satoshi Hirahara, Naoshi Hirata, Yasuhiro Hirata, Issei Hirose, Shusaku Hondo, Kumiko Hori, Shuichiro Hori, Shigeki Horiuchi, Toshihiko Igarashi, Takashi Iidaka, Yoshihisa Iio, Ryoya Ikuta, Takeo Ito, Takaya Iwasaki, Aya Kamimura, Toshihiko Kanazawa, Yasuyuki Kano, Hiroshi Katao, Satoshi Kawamoto, Tomonori Kawamura, Saeko Kita, Masaru Kobayashi, Yuhki Kohno, Toshio Kono, Masahiro Kosuga, Atsuki Kubo, Eiji Kurashimo, Satoshi Matsumoto, Takeshi Matsushima, Toru Matsuzawa, Noa Mitsui, Reiko Miura, Masatoshi Miyazawa, Tomoko Mizukami, Satoko Murotani, Satoru Nagai, Junichi Nakajima, Takashi Nakayama, Hiroaki Negishi, Kinya Nishigami, Izumi Ogino, Shiro Ohmi, Tomomi Okada, Hiroki Onaha, Shantha S.N. Gamage, Mamoru Saka, Shin'ichi Sakai, Katsuhito Sato, Toshiya Sato, Masato Serizawa, Takuo Shibutani, Junpei Shimizu, Junichi Suganomata, Kiyoko Tagami, Keisuke Takahashi, Kaori Takai, Fumiaki Takeuchi, Yasuda Takumi, Kazuo Tanaka, Ken'ichi Tatsumi, Takashi Tonegawa, Hiroaki Tsushima, Naoki Uchida, Kenji Uehira, Tomotake Ueno, Norihito Umino, Hiroo Wada, Kazutoshi Watanabe, Shigeru Watanabe, Yasuo Yabe, Tadashi Yaginuma, Mamoru Yamada, Shunroku Yamamoto, Yoshiko Yamanaka, Futoshi Yamashita, Fumihito Yamazaki, Satoshi Yui, Yohei Yukutake

    Earth, Planets and Space 59 (8) 923-928 2007年

    DOI: 10.1186/BF03352030  

    ISSN:1343-8832

    eISSN:1880-5981

    詳細を見る 詳細を閉じる

    We deployed an extremely dense temporal seismic network in the source region of the 2004 mid-Niigata Prefecture Earthquake (thrust fault) on October 23, 2004, Japan. The seismic network consisted of 145 temporary seismic stations within a 30 km squared and had been kept within approximately a month after the mainshock. High accurate hypocenters of 708 events were determined by inverting the arrival times using double-difference earthquake location algorithm. The aftershocks along the mainshock (Mw = 6.6) and the largest aftershock (Mw = 6.3) rupture zones are distributed on two 60° westward-dipping planes, located approximately 5 km apart. Conversely, the Oct. 27 aftershock (Mw = 5.8) occurred on an eastward dipping plane with a dip angle of 25° that was conjugate to the mainshock fault plane. Most of aftershocks at both northeastern and southwestern edges occurred at shallow depths with eastward-dipping planes. Epicenters of aftershocks in the southwestern region are aligned along N15°E, and rotate approximately 20° counterclockwise from the strike of the mainshock fault. This rotation of the aftershock alignments coincides with the rotation of anticline axes in the southwestern area of the source region. Furthermore, distributions of station corrections for a one-dimensional velocity model suggest that the seismic velocity at the western side of the Muikamachi-fault is lower than that at the eastern side. It is also inferred that the velocity structures in the hangingwall vary along the fault strike. The average velocity in the mainshock rupture area is higher than the periphery in the hangingwall, especially compared with the southwestern side of the hypocenter. Copyright © The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.

  77. Numerical simulation of injection for CO2 geological sequestration with a treatment of CO2 dissolution into water 査読有り

    K. Sasaki, T. Fujii, Y. Niibori, T. Ito, T. Hashida

    WATER DYNAMICS 898 45-+ 2007年

    出版者・発行元:AMER INST PHYSICS

    DOI: 10.1063/1.2721247  

    ISSN:0094-243X

    詳細を見る 詳細を閉じる

    Carbon dioxide (CO2) is considered to be one of the greenhouse gases that may most contributes to global warming on the earth. Disposal CO2 from stationary sources into subsurface has been suggested as a possible means for reducing CO2 emissions into the atmosphere. However, much remains to be done in the issues regarding the safety and reliability Of CO2 sequestration. In this study, we have developed a simulation code by using the mathematical model of multi-phase multi-component flow in porous media to analyze the flow dynamics in the subsurface. The equation of state for CO2 covering the fluid region from the triple point to supercritical region is employed to model the state of CO2 gas, liquid and supercritical state. The effect of CO2 dissolution in water on the injection behavior is taken into account by using Henry's law extended to CO2/water system. The simulation was implemented under several geological conditions inelliding gas, liquid and supercritical state to analyze optimal injection condition. The injection pressure is lowered at the lower temperature condition and the higher hydrostatic pressure condition. The lower injection pressure inav prevent the fracturing of the injection well and excessive permeation of CO2 in the reservoir. The CO2 dissolution is slightly lowefing the injection pressure and the effect on the injection pressure is negligible under the realistic hydrostatic pressure and temperature condition. It has been demonstrated that the simulation code developed in this study may be useful to provide fundamental knowledge required for the design of CO2 injection.

  78. On Reliability of Stress Determined by Hydraulic Fracturing Stress Measurement Using Transverse Fractures 査読有り

    Hayashi, K, Sato, A, Ito, T

    Geother. Resour. Coun. Trans. 31 285-290 2007年

  79. BABHY – A New Strategy of Hydrofracturing for Deep Stress Measurements 査読有り

    Ito, T, Omura, K, Ito, H

    Scientific Drilling Special Issue (1) 113-116 2007年

    DOI: 10.2204/iodp.sd.s01.38.2007  

    ISSN:1816-8957 1816-3459

  80. Effects of Thermal Stresses on Rock Permeability with Application to the Thermal Extraction from Supercritical Rock Masses

    Chiba, R, Takashima Y, Takahashi, T, Ito, T, Hayashi, K, Hashida, T

    Proc. Renewable Energy 2006 – Advanced Technology Paths to Global Sustainability – 1575-1577 2006年10月9日

  81. Estimation of Flow Pathway Structure in Enhanced Geothermal Systems by Analyzing Microseismic Events

    Ito, T, Osada, K, Baria, R

    Proc. Renewable Energy 2006 – Advanced Technology Paths to Global Sustainability – 1571-1574 2006年10月9日

  82. Application of Point Stress Method to Hydro-fracturing Tectonic Stress Measurement

    Ito, T

    Proc. of the 16th European Conference of Fracture 1117-1118 2006年7月3日

  83. Detection of Pressure and Flow Distribution in Reservoirs from Hydraulically-induced Microseismic Events and Application to the Soultz HDR Field

    Ito, T

    Workshop Proc. Stimulation of Reservoir and Induced Microseismicity 73-79 2006年6月29日

  84. Laboratory Study of Trapping Enhancement by the In-situ Reaction Method for Geological Storage of CO2

    Ito, T, Kawamura, Y, Sekine, K, Hayashi, K

    Proc. 31st Workshop Geother. Reservoir Eng. (CD-ROM) P02_04_01 2006年6月19日

  85. A New Approach for Monitoring Pressure Propagation in Reservoirs based on Microseismic Events Caused by Hydraulic Stimulation

    Ito, T, Chiba, T, Osada, K, Hayahi, K

    Proc. 31st Workshop Geother. Reservoir Eng. 31 372-377 2006年1月30日

  86. Innovative concept of hydrofracturing for deep stress measurement

    T. Ito, H. Kato, H. Tanaka

    In-Situ Rock Stress Measurement, Interpretation and Application 53-60 2006年

    出版者・発行元:TAYLOR & FRANCIS LTD

    詳細を見る 詳細を閉じる

    For the effective measurement of the reopening pressure in hydraulic fracturing, it is necessary to use the testing equipment with sufficiently small compliance. If not, there is no way to estimate the maximum stress in a plane perpendicular to a borehole, i.e. the maximum horizontal stress assuming a vertical borehole, from the reopening pressure. This limitation makes it difficult to apply the hydraulic fracturing for the measurement of the maximum stress, because the compliance of conventional equipments is generally so large. Taking account of this situation, we propose a new strategy which allows us to do the in-situ tests of hydraulic fracturing for stress measurement at depths more than I km. The system consists of two components which are (a) the compact drilling tool with a built-in mudmotor and (b) the packer tool with a built-in pump. Each of them is conveyed in drill pipe on wireline. The compact drilling tool is used to drill an additional hole with 47 nun (AQ size) in diameter and 2-3 m in length at the bottom of an original borehole, and the hydraulic fracturing is carried out in the drilled hole by using the small packer tool.

  87. Crucial effect of system compliance on the maximum stress estimation in the hydrofracturing method: Theoretical considerations and field-test verification 査読有り

    Takatoshi Ito, Akira Igarashi, Harumi Kato, Hisao Ito, Osam Sano

    EARTH PLANETS AND SPACE 58 (8) 963-971 2006年

    出版者・発行元:TERRA SCIENTIFIC PUBL CO

    DOI: 10.1186/BF03352601  

    ISSN:1343-8832

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    Why do the currently available data sets from field hydrofracturing tests indicate that the measured re-opening pressure lies close to the shut-in pressure far more often than can reasonably be expected? In order to explain such a strange phenomenon, it is necessary to take into consideration two additional factors, those of (1) a residual aperture of fracture and (2) hydraulic compliance of the test equipment, both of which are ignored in the conventional theory of hydraulic fracturing. The residual aperture causes pressure penetration into the fracture prior to opening, and its effect is to reduce the re-opening pressure by a factor of two from the value expected when the conventional theory is used. The conventional theory implies that the fracture always begins to open at a borehole pressure less than the shut-in pressure. However, due to the effect of large hydraulic compliance, the reopening pressure measured in the conventional manner becomes larger than the true reopening pressure and approaches the shut-in pressure. Contrary to this, the reopening pressure measured using the test equipment with sufficiently small compliance represents a good estimate of the true reopening pressure. This pressure is related to the maximum horizontal stress S-H, and its measured value allows us to estimate the value of S-H.

  88. Mapping of propagating pressure in reservoir from the data of microseismic events in the 1993 hydraulic stimulation at the Soultz HDR site 査読有り

    Osada, K, Ito, T, Hayashi, K, Baria, R

    GRC Transactions 29 109-114 2005年9月

  89. 微小地震情報に基づく水圧破砕時の貯留層における圧力伝播挙動の解析 査読有り

    長田和義, 伊藤高敏, 林 一夫, Roy Baria

    日本地熱学会誌 27 (3) 211-222 2005年7月

    出版者・発行元:THE GEOTHERMAL RESEARCH SOCIETY OF JAPAN

    DOI: 10.11367/grsj1979.27.211  

    ISSN:0388-6735

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    In the hydraulic stimulation, massive fluid is injected into subsurface rock through drilled wells. Then a number of micro-seismic events are commonly observed. By analyzing the data of microseismic event associated with hydraulic stimulation, we can estimate the orientation, i.e. dip and strike, of the fracture which slides to induce micro-seismic event. From the estimated orientation taking into account the in-situ stresses and the Mohr-coulomb criterion to describe the critical condition of fracture sliding, we can estimate the pore pressure at the location of sliding fracture and at the time when the sliding occurs, in other words, when micro-seismic event occurs. The estimated values of pore pressure are sorted in a certain manner for each equally-divided spatial region, i.e. block, to give spatial distribution of pore pressure and its variation with time during hydraulic stimulation. For an example, we applied this method to the micro-seismic data observed during the hydraulic stimulation performed in September 1993 at Soultz field in France. We obtained successfully the estimated pore pressure distribution.

  90. Problem for the Maximum Stress Estimation by Hydrofracturing Method and Its Potential Solution 査読有り

    Ito, T, Igarashi, A, Ito, H, Sano, O

    Proc. of the 40 th US Rock Mech. Symp. Alaska Rocks 2005 2005年6月

  91. 低温水流入に伴う熱弾性効果によるき裂透水性の変化挙動と室内実験による検証 査読有り

    伊藤高敏, 渡邉 恒, 林 一夫, Daniel Swenson

    日本地熱学会誌 27 (2) 101-113 2005年

    DOI: 10.11367/grsj1979.27.101  

    ISSN:1883-5775 0388-6735

  92. Effect of thermal deformation on fracture permeability in stressed rock masses 査読有り

    Takatoshi Ito, Daniel Swenson, Kazuo Hayashi

    Elsevier Geo-Engineering Book Series 2 (C) 673-678 2004年

    DOI: 10.1016/S1571-9960(04)80117-4  

    ISSN:1571-9960

    詳細を見る 詳細を閉じる

    We analyse the effect of thermal contraction of rock on fracture permeability. The analysis is carried out by using a 2D FEM code which can treat the coupled problem of fluid flow in fractures, elastic and thermal deformation of rock and heat transfer. In the analysis, we assume high-temperature rock with a uniformly-distributed fracture network. The rock is subjected to in-situ confining stresses. Under the conditions, low-temperature fluid is injected into the fracture network. Our results show that even under confining environment, the considerable increase in fracture permeability appears due to thermal deformation of rock, which is caused by the difference in temperature of rock and injected fluid. However, for the increase of fracture permeability, the temperature difference is necessary to be larger than a critical value, gDTc, which is given as a function of in-situ stresses, pore pressure and elastic properties of rock. © 2004 Elsevier Ltd. All rights reserved.

  93. Utilization of mud weights in excess of the least principal stress to stabilize wellbores: Theory and practical examples 査読有り

    T Ito, MD Zoback, P Peska

    SPE DRILLING & COMPLETION 16 (4) 221-229 2001年12月

    出版者・発行元:SOC PETROLEUM ENG

    ISSN:1064-6671

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    In this paper, we address the theoretical possibility of drilling with mud weights in excess of the least principal stress for cases of particularly high pore pressure or severe wellbore instability. Because lost circulation caused by hydraulic fracturing is to be avoided, we consider three critical wellbore pressures, p(frac), p(link), and p(grow). Tensile fractures initiate at the wellbore wall at p(frac) link up to form large axial fractures that are subparallel to the wellbore axis at p(link), and propagate away from the wellbore at p(grow). It is obvious that lost circulation cannot occur if the wellbore pressure during drilling is below p(frac). However, even if p(frac) is exceeded and tensile fractures are initiated at the wellbore wall, fracture propagation (and, hence, lost circulation) will be limited as long as the wellbore pressure is below p(link). Finally, if the wellbore pressure is greater than plink, the fractures will not grow away from the wellbore (and significant lost circulation will not occur) if the wellbore pressure is below p(grow), which must exceed (if only slightly) the least principal stress. In general, our modeling shows that p(frac) and p(link) can be maximized by drilling the wellbore in an optimally stable orientation, and p(grow) can be maximized with noninvading drilling muds that prevent fluid pressure from reaching the fracture tip. We apply the model that uses in-situ stress data collected in real fields, such as the South Eugene Island field in the Gulf of Mexico and the Visund field in the northern North Sea.

  94. Laboratory and field verification of a new approach to stress measurements using a dilatometer tool 査読有り

    T Ito, A Sato, K Hayashi

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 38 (8) 1173-1184 2001年12月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/S1365-1609(01)00073-9  

    ISSN:1365-1609

    詳細を見る 詳細を閉じる

    A new method is proposed for in-situ stress measurements. The stresses are estimated from the borehole pressure required to open axial fractures emanating from the borehole, similar to hydrofracture stress measurements. However, the borehole is pressurized by inflation of a dilatometer, such as a packer and a sleeve, and the borehole pressure to reopen the fractures is detected from circumferential deformation of the borehole. The fractures are induced by hydraulic fracturing or sleeve fracturing in advance. To demonstrate this method, we developed a new dilatometer tool. The tool consists essentially of a packer around which deformation transducers sensitive to circumferential strain are affixed at 10degrees-30degrees intervals. The packer is inflated to touch the borehole wall, and then the packer pressure is increased step-wise and the resultant strains recorded. Initially, the circumferential strain developed around the borehole is radially symmetric. However, this becomes strongly asymmetric once the fractures begin to open. Thus, the records of strain at different locations around the borehole indicate both the reopening pressure and the orientation of fractures. In the case of a vertical borehole, the detected reopening pressure allows us to estimate the maximum horizontal stress on condition that the minimum horizontal stress is estimated using other approaches. (C) 2002 Published by Elsevier Science Ltd.

  95. Role of Stress Controlling Flow Pathways in Geothermal Reservoirs

    T. Ito, K. Hayashi

    Proc. of the 3rd Euroconference on Rock Physics and Rock Mechanics-Thermo-Hydro-Mechanical Coupling in Fractured Rock 47 2000年11月

  96. Fracture permeability and in situ stress to 7 km depth in the KTB Scientific Drillhole 査読有り

    T Ito, MD Zoback

    GEOPHYSICAL RESEARCH LETTERS 27 (7) 1045-1048 2000年4月

    出版者・発行元:AMER GEOPHYSICAL UNION

    DOI: 10.1029/1999GL011068  

    ISSN:0094-8276

    詳細を見る 詳細を閉じる

    To better understand the mechanisms that control fluid flow and hydraulic conductivity at significant depth in the brittle crust, we have examined the relationship between fracture permeability and in situ stress in the German continental deep drillhole (the KTB main hole) through analysis of high resolution temperature profiles. Our analysis shows that over the entire 3 - 7 km depth range studied, permeable fractures and faults (i.e., those associated with distinct thermal anomalies) lie close to the Coulomb failure line for a coefficient of friction of about 0.6. This indicates that critically-stressed faults in the crust are also the most permeable faults. This includes a major Mesozoic thrust fault at 7.1 km that is being reactivated as a strike-slip fault in the current stress field. Conversely, non-critically stressed fractures and faults do not appear to be permeable as they are not associated with identifiable thermal anomalies.

  97. Laboratory verification of a new dilatmeter tool for stress measurement

    T Ito, K Hayashi, A Sato

    PACIFIC ROCKS 2000: ROCK AROUND THE RIM 881-884 2000年

    出版者・発行元:A A BALKEMA PUBLISHERS

    詳細を見る 詳細を閉じる

    In order to detect reopening of hydraulically induced axial cracks emanating from borehole, we developed a new dilatometer tool and proved it in the laboratory. The tool consists essentially of a packer around which deformation transducers sensitive to tangential strain are affixed. The packer is inflated to touch the borehole wall and then pressure is increased step-wise and the resultant strains recorded. Initially, the circumferential strain developed around the borehole is radially symmetric. However, this becomes strongly asymmetric once the cracks begin to open. Thus, the records of strain at different locations around the borehole indicate clearly the packer pressure at which the cracks begin to open. If the borehole is vertical, the detected pressure at crack opening allows us to estimate the maximum horizontal stress on condition that the minimum horizontal stress is estimated from the crack closure pressure observed in hydrofracturing test.

  98. Hydraulic fracture reopening pressure and the estimation of maximum horizontal stress 査読有り

    T Ito, K Evans, K Kawai, K Hayashi

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES 36 (6) 811-825 1999年9月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/S0148-9062(99)00053-4  

    ISSN:0148-9062

    詳細を見る 詳細を閉じる

    In hydrofracture stress measurements, the magnitude of the maximum horizontal stress, SH, is commonly estimated from the borehole pressure required to reopen an induced axial crack. Examination of the processes which govern the borehole pressure history recorded during the reopening cycle of such tests indicates two sources of error in the estimates of SH derived using the conventional method proposed by Bredehoeft et al. [Bredehoeft JD, Wolff RG, Keys WS and Shutter El 1976, Colorado. Geol. Sec. Amer. Bull., 87, 250-8]. The first arises from the failure to include a term arising from pressure penetration into the crack Drier to reopening in the force balance acting across the mouth of the induced axial cracks. The problem can be remedied by using a modified 'reopening equation' which includes pressure penetration of the crack. The second source of error is more problematic and concerns the correct identification of the true reopening pressure from the borehole pressure records. Analysis of the process of reopening aided by numerical simulations shows that the true reopening pressure is generally less than the apparent (i.e. that detected) reopening pressure. The discrepancy between true and apparent reopening pressures increases with larger hydraulic compliance of the test equipment. The compliance in question refers to that of the fluid volume between the flow meter and the crack mouth(s). Simulation of a pair of 1 m high axial cracks with 2 mu m residual hydraulic aperture in a 100 mm borehole, indicates that the system compliance must be reduced to 5 x 10(-7) m(3)/MPa to enable the true reopening pressure to be estimated to better than 10%, at flow rate is less than 10(-4) m(3)/s. This is several orders of magnitude less than applies to conventional hydrofracture systems, but is attainable for tests in small holes at shallow depth by making relatively minor system modifications. Tests at greater depth, however, would seem to require downhole measurement of flow at the packers. We validate our assertions with a field test in which reopening pressure was determined mechanically and hydraulically. (C) 1999 Elsevier Science Ltd. All rights reserved.

  99. Stress and rock mechanics issues of relevance to HDR/HWR engineered geothermal systems: review of developments during the past 15 years 査読有り

    KF Evans, FH Cornet, T Hashida, K Hayashi, T Ito, K Matsuki, T Wallroth

    GEOTHERMICS 28 (4-5) 455-474 1999年8月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/S0375-6505(99)00023-1  

    ISSN:0375-6505

    詳細を見る 詳細を閉じる

    This paper reports the findings of the Stress and rock mechanics working group of the Academic Review of Hot Dry Rock/Hot Wet Rock (HDR/HWR) Engineered Geothermal Systems convened in Sendai, Japan in 1997. Key developments in the fields of stress and rock mechanics that are relevant to the development of HDR/HWR systems and that have occurred since the last Academic Review in 1982 are described. Rock mechanics is here taken to include basic studies of fluid flow through fractures. Key unresolved issues that are important for HDR/HWR systems are also discussed. (C) 1999 CNR. Published by Elsevier Science Ltd. All rights reserved.

  100. Experimental study for stress measurements on electrical resistivity of rocks

    Y. Ito, S. Oyama, K. Hayashi

    Proceedings of the '99 Japan-Korea Joint Symposium on Rock Engineering 311 1999年8月

  101. A Study on Stress Controlling Flow Pathways in HDR/HWR Geothermal Reservoirs 査読有り

    ITO Takatoshi

    Geothermal Resources Council Transactions 223 259 1999年

  102. Utilization of mud weights in excess of the least principal stress in extreme drilling environments

    T Ito, MD Zoback, P Peska

    ROCK MECHANICS FOR INDUSTRY, VOLS 1 AND 2 253-259 1999年

    出版者・発行元:A A BALKEMA PUBLISHERS

    詳細を見る 詳細を閉じる

    We address the theoretical possibility of drilling with mud weights in excess of the least principal stress for cases of particularly severe wellbore instability. Tensile fractures initiate at the wellbore wall at Pf,,, they link up to form large axial fractures sub-parallel to the wellbore axis at P-link, and they propagate away from the wellbore at P-grow. In general, our modeling shows that P-frac and P-link can be maximized by drilling the wellbore in an optimally stable orientation, and P-grow can be maximized by using "non-invading" drilling muds, that is, those that prevent fluid pressure from reaching the fracture tip (i.e., if solids in the mud form bridges within the fracture).

  103. Stress concentration at the bottom of a borehole and its effect on borehole breakout formation 査読有り

    T Ito, K Kurosawa, K Hayashi

    ROCK MECHANICS AND ROCK ENGINEERING 31 (3) 153-168 1998年7月

    出版者・発行元:SPRINGER-VERLAG WIEN

    DOI: 10.1007/s006030050016  

    ISSN:0723-2632

    詳細を見る 詳細を閉じる

    Stress concentration at the bottom of a borehole due to the corners with small radius of curvature in an axial section and its effect on the azimuth of breakout was studied. To this end, a 3-D finite element analysis was conducted and the stress around the borehole was examined for boreholes arbitrarily oriented to three principal axes of remote stress. Results show that, in the case of high strength rock, compressive failure resulting in spalling of a borehole may occur only at the bottom of the borehole. The spalling can occur continuously with drilling, and results in continuous spalling with depth, i.e., a breakout. This type of breakout tends to form on one side of the borehole and its orientation is approximately perpendicular to the orientation of standard breakouts, inferred from the stress concentration due to the cylindrical shape of the borehole.

  104. Utilization of Directional Drilling to Maximize Wellbore Pressures during Drilling

    T. Ito, M. Zoback

    Stanford Rock Physics & Borehole Geophysics Project 68 F9-1 1998年6月

  105. 不均一な初期間隙水圧分布下におけるパルステストの解析

    伊藤 高敏

    豊田研究報告 50 25 1997年5月

  106. Two methods for hydraulic fracturing stress measurements without the ambiguous reopening pressure 査読有り

    T. Ito, A. Sato, K. Hayashi

    International journal of rock mechanics and mining sciences &amp; geomechanics abstracts 34 (3-4) 499 1997年4月

    DOI: 10.1016/S1365-1609(97)00121-4  

    ISSN:0148-9062

    詳細を見る 詳細を閉じる

    Two methods which do not use the ambiguous reopening pressure for hydraulic fracturing stress measurement are presented. The first method uses only the shut-in pressures for the transverse cracks crossing the borehole obliquely, and the second method uses the actual reopening pressure of the longitudinal crack, which coincides actually with the reopening of the crack lip at the borehole wall. The first method can estimate the range of error in the evaluated magnitudes and orientations of the remote stresses. The two methods are applied to the results of hydraulic fracturing experiments performed at the Kamaishi mine. Reliability of the evaluated stress field is confirmed by comparing the stress field with that evaluated by the over coring method. From these results, the effects of fault on the stress field are also discussed.

  107. Conventional hydrofrac method in arbitrarily oriented stress fields

    A Sato, T Ito, K Hayashi

    ROCK STRESS 107-110 1997年

    出版者・発行元:A A BALKEMA PUBLISHERS

    詳細を見る 詳細を閉じる

    The applicability of the conventional hydraulic fracturing method to arbitrarily oriented stress field has been clarified quantitatively, where the method was proposed originally for the 2D stress state. The results show that the applicability depends on the strength of rock, and if the tensile strength of rock is relatively large compared with the mean value of the in-situ stress, the state of stress in the plane perpendicular to the borehole axis can be estimated approximately from the azimuth of the induced longitudinal cracks and their reopening and shut-in pressures independently of borehole inclination.

  108. Residual stress in rock core samples and stress state at great depths

    T Ito, K Watanabe, K Hayashi

    ROCK STRESS 167-170 1997年

    出版者・発行元:A A BALKEMA PUBLISHERS

    詳細を見る 詳細を閉じる

    A new type of core-based methods is proposed to estimate the stress state at great depths. The method is based on a hypothesis on the stress in the core sample: when the core sample is under the same stress conditions as it was when under the in-situ stress, the direction of the principal stress is aligned in the same direction at all points within the core sample. Thus, the magnitudes of the in-situ stresses can be evaluated as those of the applied stresses in a laboratory experiment at which the uniformity of stress distribution in the core sample is maximized.

  109. A study for in-situ stress measurements from circumferential deformation of borehole wall due to pressurization 査読有り

    T Ito, K Hayashi

    ROCK MECHANICS TOOLS AND TECHNIQUES, VOLS 1 AND 2 891-896 1996年

    出版者・発行元:A A BALKEMA

  110. In Situ Stress Measurements by Hydraulic Fracturing for a Rock Mass with Many Planes of Weakness 査読有り

    ITO Takatoshi

    International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts 34 (1) 45 1996年

    DOI: 10.1016/S0148-9062(96)00044-7  

  111. 水圧破砕地殻応力計測におけるき製の方位類似性と地殻応力成分の信頼性評価 査読有り

    ITO Takatoshi

    日本機械学会論文集. A編 62 (603) 161-2566 1996年

    出版者・発行元:一般社団法人日本機械学会

    DOI: 10.1299/kikaia.62.2561  

    ISSN:0387-5008

    詳細を見る 詳細を閉じる

    Hydraulic fracturing rock stress measurement utilizing shut-in pressures of transverse cracks, the reliability of evaluated in situ stress state depends upon the independence of crack orientation, qualitatively speaking, the reliability improves when orientation of cracks differs significantly from each other. In order to evaluate the relationship between independence and reliability, we introduced the condition number of a matrix which is completely determined by the orientation of transverse cracks induced by hydraulic fracturing. We examined 30 sets of artificial data, each set of which consisted of ten cracks generated by random sampling, under two given stress states, and investigated the relationship between the condition number and the reliability of the estimated stress state. It was revealed that the reliability and the condition number had strong correlation and, thus, the condition number is a very useful measure of the reliability of the estimated stress state.

  112. 水圧破砕地殻応力計測におけるき裂閉口圧の高温下での測定 査読有り

    伊藤 高敏

    日本地熱学会誌 17 (3) 233-242 1995年

    DOI: 10.11367/grsj1979.17.233  

    ISSN:1883-5775 0388-6735

  113. 水圧破砕地殻応力計測法により得られた地殻応力成分の信頼性評価 査読有り

    伊藤 高敏

    日本機械学会論文集A編 61 (592) 2599-2604 1995年

    出版者・発行元:一般社団法人日本機械学会

    DOI: 10.1299/kikaia.61.2599  

    ISSN:0387-5008

    詳細を見る 詳細を閉じる

    Hydraulic fracturing stress measurement technique is the most well-known method for in situ stress measurements. However, a general method has not yet been established for estimating the reliability of the evaluated in situ stress. This paper presents a new method for estimating the reliability of the in situ stress evaluated by hydraulic fracturing stress measurement technique which utilizes a shut-in pressure and an orientation of cracks induced by hydraulic fracturing. The validity of the method was examined by applying it to two sets of artificial data constructed for eight cracks under a given stress state. The shut-in pressure for each crack was given by assuming the shut-in pressure to be equal to the normal stress acting perpendicularly to the crack. It was revealed that the shut-in pressure for each crack was most crucial for obtaining reliable results.

  114. MEASUREMENT OF IN-SITU HYDRAULIC PROPERTIES FROM THE PULSE TEST FOR THE CASE OF UNKNOWN INSITU PORE PRESSURE AND ITS APPLICATION TO HDR MODEL FIELDS 査読有り

    T ITO, Y HIROSE, K HAYASHI

    GEOTHERMAL RESOURCES COUNCIL TRANSACTIONS, VOL 18 18 445-451 1994年

    出版者・発行元:GEOTHERMAL RESOURCES COUNCIL

    ISSN:0193-5933

  115. IN-SITU STRESS MEASUREMENT BY HYDRAULIC FRACTURING AT THE KAMAISHI MINE 査読有り

    K HAYASHI, T ITO

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES & GEOMECHANICS ABSTRACTS 30 (7) 951-957 1993年12月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    ISSN:0148-9062

    詳細を見る 詳細を閉じる

    Hydraulic fracturing stress measurement was performed by using a 30m-deep well drilled in the Kamaishi iron mine. Eight transverse cracks crossing the well obliquely were obtained. By re-plotting the shut-in curves, i.e., the pressure-time records after shut-in, into dT/dP vs. P plots (T:time, P: wellbore pressure), shut-in pressure was determined objectively. By using the shut-in pressure of the eight transverse cracks, three-dimensional stress field was evaluated based on the assumption that the shut-in pressure of a transverse crack gave a good estimate of the magnitude of the normal stress acting perpendicularly to the crack. Finally, the reliability of the evaluated stress field is discussed.

  116. ANALYSIS OF CRACK REOPENING BEHAVIOR FOR HYDROFRAC STRESS MEASUREMENT 査読有り

    T ITO, K HAYASHI

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES & GEOMECHANICS ABSTRACTS 30 (7) 1235-1240 1993年12月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/0148-9062(93)90101-I  

    ISSN:0148-9062

    詳細を見る 詳細を閉じる

    The relation among the so-called reopening pressure, in situ stresses and injection flow rate was clarified theoretically and experimentally for the case that a transverse crack is induced perpendicularly to a borehole axis in hydraulic fracturing stress measurements. The results are summarized as follows. The reopening pressure, i.e. the borehole pressure at which the borehole pressure - time history during pressurization clearly deviates from a linear relationship, is basically governed by the in situ compressive stress normal to the crack plane, S(v). Its magnitude decreases and approaches the magnitude of S(v) with decreasing injection flow rate.

  117. 水圧破砕地殻応力計測における横き裂開口挙動の解析 査読有り

    伊藤 高敏

    日本機械学会論文集A編 59 (561) 1287-1291 1993年

    出版者・発行元:日本機械学会

    DOI: 10.1299/kikaia.59.1287  

    ISSN:0387-5008

    詳細を見る 詳細を閉じる

    The reopening behavior of a transverse crack which is induced on the surface of a borehole by hydraulic fracturing is analyzed to establish the methodology for hydraulic fracturing tectonic stress measurements, where, as a typical transverse crack, a penny-shaped crack which is induced perpendicularly to the borehole axis is considered. To this end, a model is constructed for analyzing the coupled problem of fluid flow in the crack and crack reopening behavior in an impermeable rock. The model takes into account the fact that the crack does not reclose perfectly upon deflation due to crack surface damage and minor shear displacement. The results show that the apparent reopening pressure, i.e., borehole pressure at which the pressure-time history clearly deviates from linearity, decreases and approaches the compressive tectonic stress normal to the crack plane with decreasing injection flow rate, and that it is almost proportional to the compressive tectonic stress independently of injection flow rate.

  118. ANALYSIS OF STRESS-INDUCED WELLBORE BREAKOUTS IN AN ARBITRARILY ORIENTED TECTONIC STRESS-FIELD 査読有り

    T ITO, K HAYASHI, MD ZOBACK

    JSME INTERNATIONAL JOURNAL SERIES I-SOLID MECHANICS STRENGTH OF MATERIALS 35 (3) 265-270 1992年7月

    出版者・発行元:JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG

    ISSN:0914-8809

    詳細を見る 詳細を閉じる

    A detailed study is presented of a case of stress induced wellbore breakouts observed where none of the principal axes of the tectonic stresses coincides with a wellbore axis. The observed depth and azimuth of breakout occurrence were compared with theoretical predictions based on the elastic stress field induced around a wellbore in a generalized 3-D stress field. The stress field had previously been studied using 3-D hydrofrac stress measurement. Results show that, when the uniaxial compressive strength of the rock is known, the depth and azimuth of breakout occurrence can be used as a reliable method to confirm the tectonic stress magnitudes determined by hydraulic fracturing.

  119. Regulation of water flow by actin-binding protein-induced actin gelatin 査読有り

    T. Ito, A. Suzuki, T. P. Stossel

    Biophysical Journal 61 (5) 1301-1305 1992年

    DOI: 10.1016/S0006-3495(92)81938-0  

    ISSN:0006-3495

    詳細を見る 詳細を閉じる

    Actin filaments inhibit osmotically driven water flow (Ito, T., K.S. Zaner, and T.P. Stossel. 1987. Biophys. J. 51: 745–753). Here we show that the actin gelation protein, actin-binding protein (ABP), impedes both osmotic shrinkage and swelling of an actin filament solution and reduces markedly the concentration of actin filaments required for this inhibition. These effects depend on actin filament immobilization, because the ABP concentration that causes initial impairment of water flow by actin filaments corresponds to the gel point measured viscometrically and because gelsolin, which noncovalently severs actin filaments, solates actin gels and restores water flow in a solution of actin cross-linked by ABP. Since ABP gels actin filaments in the periphery of many eukaryotic cells, such actin networks may contribute to physiological cell volume regulation. © 1992, The Biophysical Society. All rights reserved.

  120. 水圧破砕地殻応力計測における縦き裂開口圧と地殻応力の関係 査読有り

    伊藤 高敏

    日本機械学会論文集A編 58 (545) 1992年

    DOI: 10.1299/kikaia.58.72  

  121. 水圧破砕地殻応力計測のためのシャットイン後の横き裂閉口挙動の解析 査読有り

    伊藤 高敏

    日本機械学会論文集A編 58 (547) 367-371 1992年

    出版者・発行元:日本機械学会

    DOI: 10.1299/kikaia.58.367  

    ISSN:0387-5008

    詳細を見る 詳細を閉じる

    Closure process of a transverse crack crossing a wellbore is analyzed to discuss physical meanings of the pressure decay curve after shut-in during hydraulic fracturing tectonic stress measurements, where the crack is assumed to be perpendicular to the wellbore axis and one of the principal axes of the tectonic stress is assumed to be parallel to the wellbore axis. The analysis is based on the linear theory of elasticity and linear fracture mechanics. It is shown that the whole crack closes instantaneously when the downhole water pressure is equal to the compressive tectonic stress acting perpendicularly to the crack plane. The instantaneous crack closure appears as a point of maximum curvature on the pressure decay curve after shut-in. Therefore, the compressive tectonic stress normal to the crack plane is determined as the pressure at the point of maximum curvature. Although the point of maximum curvature appears less clearly on pressure decay curve when the fluid loss coefficient is large, the instantaneous crack closure can always be detected clearly by utilizing the relation of the inverse of the decrease rate of the downhill water pressure Vs the downhill pressure.

  122. CHARACTERISTICS OF SHUT-IN CURVES OF TRANSVERSE CRACKS IN HYDRAULIC FRACTURING STRESS MEASUREMENTS 査読有り

    T ITO, K HAYASHI

    20TH ANNIVERSARY - GEOTHERMAL RESOURCES COUNCIL 16 651-656 1992年

    出版者・発行元:GEOTHERMAL RESOURCES COUNCIL

    ISSN:0193-5933

  123. PHYSICAL BACKGROUND TO THE BREAKDOWN PRESSURE IN HYDRAULIC FRACTURING TECTONIC STRESS MEASUREMENTS 査読有り

    T ITO, K HAYASHI

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES & GEOMECHANICS ABSTRACTS 28 (4) 285-293 1991年7月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    DOI: 10.1016/0148-9062(91)90595-D  

    ISSN:0148-9062

    詳細を見る 詳細を閉じる

    A new theory is presented to interpret the breakdown pressure which is the wellbore pressure at fracture initiation in hydraulic fracturing tectonic stress measurements. The theory is able to explain the effects of wellbore diameter and pressurization rate on the breakdown pressure. It was shown that these effects were explainable in a simple way by taking into account the effective stress distribution beyond a wellbore surface and by applying a newly-constructed fracture criterion. The criterion assumes the fraction initiation occurs when the maximum tensile effective stress reaches the tensile strength of a rock at a point that is not on the wellbore surface but is inside the rock. The distance between that point and the point of stress concentration is a material constant. In order to verify the present theory, laboratory hydraulic fracturing experiments were performed on cubical rock specimens under uniaxial compression. Results show that experimental breakdown pressures decrease with the increasing wellbore diameter and increase with the pressurization rate. In all cases, the experimental results agree perfectly well with the prediction based on the present theory contrary to the prediction based on the conventional theory.

  124. 水圧破砕地殻応力計測における縦き裂開口挙動の解析 査読有り

    伊藤 高敏

    日本機械学会論文集A編 57 (540) 1715-1719 1991年

    出版者・発行元:日本機械学会

    DOI: 10.1299/kikaia.57.1715  

    ISSN:0387-5008

    詳細を見る 詳細を閉じる

    The reopening behavior of longitudinal cracks which are induced by hydraulic fracturing on the surface of a borehole is analyzed to establish the methodology of hydraulic fracturing tectonic stress measurements. To this end, a model is constructed to analyze the coupled problem of fluid flow in the crack and the crack reopening behavior in impermeable rock, based on the linear theory of elasticity and also on the linear fracture mechanics and taking into account that the crack does not reclose perfectly upon deflation due to crack surface damage and some minor shear displacement. The results show that the borehole pressure at the instant when the crack reopening occurs is just half of the pressure value predicted by the conventional theory. The borehole pressure at which the pressure-time history apparently deviates from a linear behavior is somewhat higher than the true pressure value at the crack reopening, and it increases with water injection rate.

  125. Determination of the Minimum Horizontal Principal Stress from Pressure Decay after Breakdown in Hydraulic Fracturing 査読有り

    ITO Takatoshi

    Geothermal Resources Council Transactions 15 1991年

  126. き裂閉口時に観測される新たな水圧データを用いた水圧破砕地殻応力計測法の提案 査読有り

    伊藤 高敏

    日本機械学会論文集A編 57 (542) 2345-2348 1991年

    出版者・発行元:日本機械学会

    DOI: 10.1299/kikaia.57.2345  

    ISSN:0387-5008

    詳細を見る 詳細を閉じる

    A concept of crack closure pressure is proposed for evaluating tectonic stresses by the hydraulic fracturing stress measurement technique, based on the linear theory of elasticity and the linear fracture mechanics. The crack closure pressure is defined as a pressure value at a turning point appearing in the decrease rate of the downhole pressure vs the downhole pressure curve after the complete closure of the pressurizing circuit for hydraulic fracturing, i.e., shut-in. This is interpreted as a pressure at the instant when the crack which was induced by the hydraulic fracturing on the surface of a borehole closes completely after the shut-in. The relationship between the crack closure pressure and the tectonic stresses is very simple, and no material constants, such as the fracture toughness and hydraulic properties of the rock, appear in the relationship. Thus, it can be applied as a new and extremely useful formula for evaluating tectonic stresses by the hydraulic fracturing tectonic stress measurement technique.

  127. 水圧破砕地殻応力計測の破砕圧に及ぼす水の浸透の影響と破砕圧の評価法 査読有り

    伊藤 高敏

    日本機械学会論文集A編 56 (526) 1432-1435 1990年

    出版者・発行元:一般社団法人日本機械学会

    DOI: 10.1299/kikaia.56.1432  

    ISSN:0387-5008

    詳細を見る 詳細を閉じる

    A new method is proposed for the estimation of the so-called breakdown pressure in the hydraulic fracturing tectonic stress measurements. The stress field around the well bore was analyzed taking into account the influence of the fluid penetration into the porous rock due to the pressurization of the well bore. By the use of the stress field, the breakdown pressure, i. e., the well bore pressure required to induce cracks on the well bore was estimated based on a newly constructed fracture criterion. The criterion determines the breakdown pressure as a pressure value at which the maximum tensile effective stress at a characteristic depth beyond the well bore surface, reaches the tensile strength of the rock. To verify the new method, laboratory hydraulic fracturing experiments were conducted on cubical rock specimens under uniaxial compression. Results show that the breakdown pressures predicted by the classical method are erroneously lower than the experimental data when the uniaxial compressive stress is large. On the other hand, the breakdown pressures predicted by the present method perfectly agree with the experimental data independent of the magnitude of the uniaxial compressive stress.

  128. 坑井近傍の応力勾配を考慮した破壊基準に基づく水圧破砕における破砕圧評価に関する基礎的研究 査読有り

    伊藤 高敏

    資源・素材学会誌 106 (3) 1990年

    DOI: 10.2473/shigentosozai.106.115  

  129. INSITU STRESS DETERMINATION BY HYDRAULIC FRACTURING - A METHOD EMPLOYING AN ARTIFICIAL NOTCH 査読有り

    K HAYASHI, T ITO, H ABE

    INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES & GEOMECHANICS ABSTRACTS 26 (3-4) 197-202 1989年7月

    出版者・発行元:PERGAMON-ELSEVIER SCIENCE LTD

    ISSN:0148-9062

  130. A NEW METHOD FOR THE DETERMINATION OF INSITU HYDRAULIC-PROPERTIES BY PRESSURE PULSE TESTS AND APPLICATION TO THE HIGASHI HACHIMANTAI GEOTHERMAL-FIELD 査読有り

    K HAYASHI, T ITO, H ABE

    JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH AND PLANETS 92 (B9) 9168-9174 1987年8月

    出版者・発行元:AMER GEOPHYSICAL UNION

    ISSN:0148-0227

  131. A New In-Situ Tectonic Stress Measurements and its Application to a Geothermal Model Field 査読有り

    K. Hayashi, T. Shoji, H. Niitsuma, T. Ito, H. Abé

    Geothermal Resources Council Trans. 9 99-104 1985年

  132. Growth Behavior of Hydraulically Created Crack and its Size Evaluation Using Well Logging Data - Crustal Rock Fracture Mechanics Approach - 査読有り

    T. Shoji, K. Hayashi, T. Kojima, T. Ito, H. Takahashi, H. Abé

    Geothermal Resources Council Trans. 9 579-584 1985年

︎全件表示 ︎最初の5件までを表示

MISC 62

  1. テレワークと温泉熱利用による環境負荷低減効果の評価:鳴子地域のケーススタディ

    長谷川諒, 鈴木杏奈, 伊藤高敏, 稗貫峻一, 窪田ひろみ

    日本地熱学会学術講演会講演要旨集 2021 (3) 111-122 2021年

    出版者・発行元:日本地熱学会

    DOI: 10.11367/grsj.44.111  

    ISSN:0388-6735

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    資源・素材(Web) 2020 2020年

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    手塚和彦, 山本俊也, 伊藤高敏, 小川浩司, 横山幸也, 船戸明雄

    石油技術協会誌(CD-ROM) 85 (1-6) 2020年

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    日本地熱学会学術講演会講演要旨集 2019 35-35 2019年11月

  5. Topological data analysis for estimating flow characteristics of 3D fracture network

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    Proceedings of the 16th International Conference of Flow Dynamics 598-599 2019年11月

  6. 二重コアリングで得られたコアを用いる地殻応力測定法の研究

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    資源・素材(Web) 2019 2019年

  7. 二重解放コアを用いた地殻応力測定法の研究開発

    伊藤高敏, 手塚和彦, 横山幸也, 船戸明雄

    日本地熱学会学術講演会講演要旨集 2019 2019年

  8. Crustal stress states around Nojima fault measured by using a new testing system for hydraulic fracturing

    Tatsuya Yokoyama, Aiming Lin, Weiren Lin, Takashi Danjo, Takatoshi Ito

    2018 AGU Fall Meeting, 2018年12月

  9. A new flow model based on pore-scale network method for supercritical CO2 fracturing

    Liu Bailong, Suzuki Anna, Ito Takatoshi

    Proceedings of the 15th International Conference on Flow Dynamics 2018年11月

  10. Link between tracer and microseismic analysis to comprehensive understanding of hydraulic feature of fractured geothermal reservoir

    Suzuki Anna, Mukuhira Yusuke, Ito Takatoshi, Horne Ronald N, Fehler M. C, Kang Peter

    Proceedings of the 18th International Symposium on Advanced Fluid Information 66-67 2018年11月

  11. Analysis of rock fracture pattern and fluid flow by persistent homology

    Miyazawa Miyuki, Suzuki Anna, Okamoto Atsushi, Shimizu H, Obayashi Ippei, Ito Takatoshi

    Proceedings of the 15th International Conference on Flow Dynamics 2018年11月

  12. 数値シミュレーションと組み合わせた構造解析による蛇紋岩の形成メカニズム推定

    宮澤美幸, 鈴木杏奈, 岡本敦, 清水浩之, 大林一平, 平岡裕章, 平岡裕章, 伊藤高敏

    日本地質学会学術大会講演要旨 125th 116 2018年9月

    ISSN:1348-3935

  13. 主応力比の大きい岩盤応力状態下における水圧破砕試験でのき裂挙動

    横山幸也, 坂口清敏, 伊藤高敏

    資源・素材(Web) 2018 2018年

  14. Estimation of crack width in porous media by nano/micro particles 査読有り

    Junzhe Cui, Anna Suzuki, Satoshi Uehara, Keiichi Shirasu, Takatoshi Ito

    Proceedings of the 15th International Conference of Flow Dynamics 2018年

  15. Hybrid focal mechanism determination: Constraining focal mechanisms of injection induced seismicity using in situ stress data

    Y. Mukuhira, Y. Mukuhira, K. Fuse, M. Naoi, M. C. Fehler, H. Moriya, T. Ito, H. Asanuma, M. O. Häring

    Geophysical Journal International 215 1427-1441 2018年1月1日

    DOI: 10.1093/GJI/GGY333  

    ISSN:0956-540X

    詳細を見る 詳細を閉じる

    © The Author(s) 2018. Determining the focal mechanisms of injection induced microseismicity provides beneficial information not only for understanding the features of induced seismicity but also for characterizing the fracture system in the reservoir. However, focal mechanisms ofmicroseismicity are often not well determined with first motion information alone due to limited station coverage. We propose a new method to better constrain first motion focal mechanisms of fluid-induced seismicity by introducing in situ stress information estimated from borehole analysis and wellhead pressure. Since injection induced seismicity is dominantly caused by increases of pore pressure, we can use in situ stress magnitude/orientation information and the injection wellhead pressure to constrain the range of focal mechanisms. Then, the range of possible focal mechanisms estimated from available first motion data is constrained by superposing the range of focal mechanisms that can slip from the in situ stress condition. The use of the combined sets of information places a better constraint on focal mechanisms than can be obtained from either of the individual data sets. We apply our method to the microseismic data recorded during the hydraulic stimulation in Basel, Switzerland where the stress state is known from borehole measurements. Our method successfully constrains the range of focal mechanisms, though the degree of constraint is dependent on the distribution of possible focal mechanisms that are consistent with the first motions and the distribution that are consistent with the stress condition. We compared the range of focal mechanisms constrained by our method using data from only nearby stations with well-constrained focal mechanisms determined from first motions that are recorded by more than 50 surface stations. In the best case, 80 per cent of the focal mechanisms that are consistent with the first motion data were removed because they were inconsistent with the stress data. The constrained range of focal mechanisms includes the true focal mechanisms with significantly high probability of 0.86 even considering the uncertainty in stress information that is used for constraint. This demonstrates the ability of our method to constrain the range of focal mechanisms in situations with limited station coverage, and the benefits of introducing other geophysical data into seismological analyses.

  16. 南アフリカ金鉱山M2-5.5地震発生場掘削ICDPワークショップ報告

    小笠原宏, 矢部康男, 伊藤高敏, ワークショップ参加者

    J-DESCニュースレター (9) 14 2016年4月

  17. 主応力比の大きい岩盤応力下における水圧破砕試験でのき裂の再開口と閉口挙動に関する考察

    横山幸也, 坂口清敏, 伊藤高敏, LIN Weiren

    地盤工学研究発表会発表講演集(CD-ROM) 51st 2016年

  18. 非在来型資源

    伊藤高敏

    岩の力学連合会50周年記念式典 記念誌「岩の力学 50年の歩みと未来への展望」 149-152 2014年6月

    出版者・発行元:岩の力学連合会

  19. 地下開発におけるフラクチャリング技術とメタンハイドレート開発への応用研究

    伊藤 高敏, 手塚 和彦

    化学工学 = Chemical engineering 75 (12) 783-785 2011年12月5日

    出版者・発行元:化学工学会

    ISSN:0375-9253

  20. Development of borehole tangential deformation gage and its application for determining the stress in rock

    A. Igarashi, T. Ito, K. Sekine, K. Hayashi

    Proceeding of the 42nd US Rock Mech.Symp. 2008年

  21. 地熱型再生可能エネルギー利用の実用化研究

    伊藤高敏, 新堀雄一

    伝熱 46 (196) 285-38 2007年7月

  22. 195 CO_2地下貯留のためのCO_2圧入挙動の数値シミュレーションに関する研究(学生賞III)

    佐々木 健太, 藤井 孝志, 新堀 雄一, 伊藤 高敏, 橋田 俊之

    講演論文集 2007 (42) 187-188 2007年3月13日

    出版者・発行元:一般社団法人日本機械学会

  23. ボアホール変形メーターの試作と大滝根鉱山での検証試験

    五十嵐 哲, 伊藤 高敏, 林 一夫

    春季大会講演集. I, 資源編 18 (1) 109-110 2006年3月27日

    ISSN:1343-9898

  24. CO2地中固定のための人工バリアー形成の室内実験

    伊藤 高敏, 川村 典久, 関根 孝太郎, 林 一夫

    春季大会講演集. I, 資源編 18 (2) 1-2 2006年3月27日

    ISSN:1343-9898

  25. 先進地熱エネルギー技術の新展開

    伊藤 高敏

    日本機械学會誌 = Journal of the Japan Society of Mechanical Engineers 108 (1045) 928-929 2005年12月5日

    出版者・発行元:一般社団法人日本機械学会

    ISSN:0021-4728

  26. 先進地熱エネルギー技術の新展開

    伊藤 高敏

    日本機械学会誌 108 (1045) 110-111 2005年12月

  27. 臨界き裂に基づく地殻応力評価法に及ぼすき裂配向性の影響

    伊藤 高敏, 林 一夫

    春季大会講演集. I, 資源編 17 (1) 157-158 2005年3月28日

    ISSN:1343-9898

  28. き裂開口検出を目的とした坑壁変形センサの現位置試験

    五十嵐 哲, 加藤 春實, 伊藤 高敏, 林 一夫

    春季大会講演集. I, 資源編 17 (1) 159-160 2005年3月28日

    ISSN:1343-9898

  29. 次世代地熱開発技術の現状と将来(肘折高温岩体プロジェクトの検証) : 貯留層形成

    伊藤 高敏, 浅沼 宏, 岡部 高志, 唐澤 広和, 竹原 孝, 手塚 和彦

    日本地熱学会学術講演会講演要旨集 2004 A19 2004年11月20日

  30. 室内水圧破砕試験におけるせん断型き裂の開口・閉口挙動

    関根 孝太郎, 奥 晴行, 根本 克己, 伊藤 高敏, 林 一夫

    日本地熱学会学術講演会講演要旨集 2004 A25 2004年11月20日

  31. 微小地震情報に基づく雄勝HDRフィールドにおける地下流路空間分布の推定

    長田 和義, 伊藤 高敏, 海江田 秀志, 林 一夫

    日本地熱学会学術講演会講演要旨集 2004 A34 2004年11月20日

  32. 温度変化による応力低下モデルに基づく葛根田地熱地域における注水データの解析

    伊藤 高敏, 梶原 竜哉, 林 一夫

    日本地熱学会学術講演会講演要旨集 2003 63-63 2003年11月20日

  33. 高温・高圧水環境下における岩石中への水圧注入挙動の評価に関する研究

    千葉 隆一, 高嶋 洋平, 伊藤 高敏, 林 一夫, 橋田 俊之

    日本地熱学会学術講演会講演要旨集 2003 P03 2003年11月20日

  34. 微小地震を用いたソルツフィールドにおける間隙水圧分布とその時間変化の推定

    長田 和義, 伊藤 高敏, 林 一夫, BARIA R.

    日本地熱学会学術講演会講演要旨集 2003 87-87 2003年11月20日

  35. ボアホール周方向変位計測のための新型センサーと地殻応力評価への応用

    伊藤 高敏, 小野 雅俊, 林 一夫

    春季大会講演集. I, 資源編 15 (1) 195-196 2003年3月27日

    ISSN:1343-9898

  36. Role of stress-controlled flow pathways in HDR geothermal reservoirs

    Takatoshi Ito, Kazuo Hayashi

    Pure and Applied Geophysics 160 (5-6) 1103-1124 2003年

    出版者・発行元:Birkhauser Verlag AG

    DOI: 10.1007/PL00012563  

    ISSN:0033-4553

    詳細を見る 詳細を閉じる

    We addressed effects of in situ stress on the formation of flow pathways in fractured rocks in geothermal reservoirs, especially for HDR projects. Here we focused on fractures which are critically-stressed, causing shear slip in a current stress field. The sliding is likely to break sealing in the fractures and, as a result, to increase their permeability. Such a mechanism is possibly significant under high-temperature conditions at geothermal fields because of temperature enhancement on chemical reactions for the sealing. We present a procedure to estimate the orientation of the critically-stressed fractures relative to axes of in situ principal stress with the aid of the Mohr diagram. The procedure allows us to evaluate intuitively how the orientation changes with factors such as magnitude of in situ principal stresses and pore pressure. We applied the procedure to estimate possible orientations of the critically-stressed fractures in major HDR test sites. Results show that overall alignments of microseismicity during hydraulic stimulation are within predicted ranges for possible orientations of the critically-stressed fractures. Furthermore, it was found that if the state of in situ stress is not favorable to cause sliding of natural fractures, it tends to lead a high wellhead pressure at hydraulic stimulation and a high recovery rate at circulation. On the other hand, if the state of in situ stress is favorable for sliding, it tends vice versa to lead a low wellhead pressure at hydraulic stimulation and a low recovery rate at circulation.

  37. A Newly-Developed Transducer to Measure Circumferential Deformation of Borehole Wall in Sleeve Fracturing and its Application to Stress Estimation

    T. Ito, K. Hayashi

    Proceedings of 3rd. International Symposium of Rock Stress 289-294 2003年

  38. Numerical Study on Optimum Injection Temperature Inferred from Coupled-Hydro-Thermal-Mechanical Behavior of Rock

    T. Ito, D. Swenson, K. Sekine, K. Hayashi

    Geothermal Resources Council Transaction 27 695-698 2003年

  39. 坑井壁面の引張き裂 (Drilling Induced Tensile Wall Fracture) 発生挙動の室内実験による検討

    伊藤 高敏, 岩谷 悠平, 林 一夫

    春季大会講演集. I, 資源編 14 (1) 91-92 2002年3月28日

    ISSN:1343-9898

  40. 岩石の電気伝導性を利用した坑井壁面き裂の開口評価に関する研究

    伊藤 高敏, 斎藤 政人, 林 一夫

    東北大学流体科学研究所報告 13 39-52 2002年

    出版者・発行元:東北大学流体科学研究所

    ISSN:0916-2860

  41. 冷却に伴う岩体透水性の変化挙動

    伊藤 高敏, 石井 泰朗, 林 一夫

    日本地熱学会学術講演会講演要旨集 2001 A07 2001年12月1日

  42. 水圧破砕中に発生した微小地震に基づく貯留層内の流路構造評価法の提案

    伊藤 高敏, 長田 和義, 林 一夫

    日本地熱学会学術講演会講演要旨集 2001 P18 2001年12月1日

  43. 真のき裂開口圧による最大地殻応力評価法とその実用化システム

    伊藤 高敏, 加藤 春實, 狩野 嘉昭, 林 一夫

    資源・素材 2001 17-18 2001年9月24日

    ISSN:0919-7915

  44. 透水性き裂と地殻応力の関係に基づく地殻応力評価の可能性

    伊藤 高敏, 斉藤 美歌, 林 一夫

    一般発表(研究・業績発表)講演要旨集 2001 (1) 203-204 2001年3月1日

    ISSN:0919-293X

  45. Modeling of residual stress and micro-crack in rock caused by stress relief due to coring

    T Ito, K Hayashi

    ROCK MECHANICS: A CHALLENGE FOR SOCIETY 493-498 2001年

    出版者・発行元:A A BALKEMA PUBLISHERS

    詳細を見る 詳細を閉じる

    We proposed a model to estimate residual stresses and discussed the stress drive cracking in a core. Numerical experiments based on the model show that stress relief due to core drilling will cause in the core the residual stress with magnitude of 20 - 30 % of averaged in-situ stress for the case of granite. The residual stress in quartz is always compressive, and that in feldspar is tensile on average. When the tensile residual stress is sufficient to induce micro-cracks in the core, they tend to be induced in feldspar normally to in-situ maximum compressive stress. The tendency is clear in the case when both tensile strength of feldspar and quartz content of rock are small or both of them are large, however, it is uncertain in the other cases.

  46. 水圧破砕法の標準法

    伊藤 高敏, 林 一夫

    資源・素材 2000 (1) 81-84 2000年10月3日

    ISSN:0919-7915

  47. 雄勝及びソルツフィールドにおけるHDR/HWR型地熱貯留層の構造と地殻応力の関係

    伊藤 高敏, 森谷 祐一, 林 一夫

    日本地熱学会学術講演会講演要旨集 1999 1999年12月1日

  48. HDR/HWR型地熱貯留層の形成機構に関する最近の知見

    伊藤 高敏, 林 一夫

    資源・素材 1999 (1) 117-120 1999年11月1日

    ISSN:0919-7915

  49. 地殻応力と岩石コア中の残留応力の関係についての二次元有限要素モデルによる理論解析

    伊藤 高敏, 渡辺 耕一郎, 林 一夫

    一般発表(研究・業績発表)講演要旨集 1997 (1) 254-254 1999年3月25日

    ISSN:0919-293X

  50. 室内実験によるボアホール変形直接計測法の検討と地殻応力評価への応用

    佐藤 晃, 伊藤 高敏, 林 一夫

    一般発表(研究・業績発表)講演要旨集 1997 (1) 91-91 1999年3月25日

    ISSN:0919-293X

  51. 岩石電気抵抗の応力による変化特性と地殻応力評価

    伊藤 高敏, 小山 直, 林 一夫

    一般発表(研究・業績発表)講演要旨集 1999 (1) 134-135 1999年3月

    ISSN:0919-293X

  52. 掘削プロセスを考慮したボアホールブレイクアウト形成過程の数値シミュレーション

    伊藤 高敏, 服部 明, 林 一夫

    一般発表(研究・業績発表)講演要旨集 1999 (1) 74-75 1999年3月

    ISSN:0919-293X

  53. 水圧破砕法による釜石フィールドの現位置応力計測

    伊藤 高敏, 佐藤 晃, 林 一夫

    資源・素材 1996 (2) 91-94 1996年10月21日

    ISSN:0919-7915

  54. パルステスト透水特性評価法におよぼす不均一な初期間隙水圧分布の影響の解析

    伊藤 高敏, 大原 常好, 林 一夫

    一般発表(研究・業績発表)講演要旨集 1996 (1) 173-173 1996年3月29日

    ISSN:0919-293X

  55. 三次元地殻応力場とボアホールブレイクアウトの関係

    伊藤 高敏, 林 一夫

    資源・素材 1995 9-12 1995年9月18日

    ISSN:0919-7915

  56. ボアホール変形挙動に基づく地殻力学情報評価のための基礎研究

    伊藤 高敏, 林 一夫

    資源・素材 1995 9-9 1995年9月18日

    ISSN:0919-7915

  57. ボアホールブレイクアウト発生に及ぼす坑底応力場の影響

    伊藤 高敏, 黒澤 宏一, 林 一夫

    一般発表(研究・業績発表)講演要旨集 1995 (1) 67-67 1995年3月28日

    ISSN:0919-293X

  58. Evaluation of In Situ Hydraulic Properties of Formation at Great Depth

    K. hayashi, T. Ito, H. Abe

    Geothermal Sciences and Technology 4 (3) 145-157 1995年

  59. 大深度地下岩体の原位置通水特性の計測評価法に関する研究

    林 一夫, 伊藤 高敏

    地下水学会誌 36 (2) 147-154 1994年

    出版者・発行元:公益社団法人 日本地下水学会

    DOI: 10.5917/jagh1987.36.147  

    ISSN:0913-4182

    詳細を見る 詳細を閉じる

    In the course of field experiments demonstrating engineering feasibility of HDR (Hot Dry Rock) geothermal heat extraction conducted in USA, UK and Japan, low recovery rate of water, which circulates through the heat extraction system consisting of injection and production wellbores and reservoir cracks, has been revealed to be one of the most serious problems against realizing the concept of HDR geothermal heat extraction. Thus it is definitely desirable to be able to estimate the amount of waterloss from the reservoir cracks beforehand prior to hydraulic fracturing for creating the reservoir cracks. The recovery rate of water is directly relating to the in-situ hydraulic properties of the rock mass which is surrounding the reservoir cracks. In the present paper, we propose a new method for measuring insitu hydraulic properties of a rock mass at great depth, more than a thousand meters. The method is based on the analysis of flow of water from the pressurized interval of a straddle packer system, set in a wellbore, back to the sections of wellbore outside the straddle packer system due to permeation through the rock. The method utilizes the time variation of the volumetric flow rate of the back flow stated above for a given level of pressure in the pressurized interval. Since this method can be applied to a variety of levels of the pressure in the pressurized interval, it will be possible to estimate the dependency of hydraulic properties on the reservoir pressure by applying the method proposed in the present paper.

  60. INVERSE PROBLEM ON THE EVALUATION OF HYDRAULIC-PROPERTIES OF ROCKS DEEP IN THE EARTHS CRUST AND EFFECT OF TUBULAR COMPLIANCE

    K HAYASHI, K NISHIBE, T ITO, H ABE

    JSME INTERNATIONAL JOURNAL SERIES I-SOLID MECHANICS STRENGTH OF MATERIALS 34 (4) 459-463 1991年10月

    出版者・発行元:JAPAN SOC MECHANICAL ENGINEERS SANSHIN HOKUSEI BLDG

    ISSN:0914-8809

    詳細を見る 詳細を閉じる

    The pressure decay process during the so-called pressure pulse test is analyzed for evaluating in situ hydraulic properties of rocks deep in the earth's crust. The present analysis takes the effects of the compliance of the tubular connecting the straddle packer to the pressurizing pump and the compliance of the well bore on the pressure decay process into account; these effects are ignored in the conventional approach. The results show that the pressure decay curve is highly dependent on the tubular compliance, and, as a result, the hydraulic properties obtained using the conventional method, which assumes that the tubular is rigid against pressure, induce large errors. Based on the analysis, a new method is proposed for evaluating in situ hydraulic properties from pressure decay curves, taking the effect of the tubular compliance into account, and the method was successfully applied to a set of experimental data of the pressure pulse test performed at a geothermal model field.

  61. Development of an Automatic and Objective Method for Evaluating Hydraulic Properties of Formations in a Depth

    K. Hayashi, K. Niiyama, T. Ito, H. Abe

    Geothermal Resoureces council Transactions 15 477-482 1991年

  62. Scale Effect in Breakdown Pressure of Hydraulic Stress Mesurements

    T. Ito, K. Hayashi

    Scale Effects in Rock Masses, ed. A. P. Da Cunha, Balkema 289-295 1990年

︎全件表示 ︎最初の5件までを表示

書籍等出版物 3

  1. Proceedings of the 6th International Symposium on In-situ Rock Stress

    Ito, T

    ISRM Specialized Conference 2013 2013年8月

  2. Nano-Mega Scale Flow Dynamics in Energy System

    Maruyama, S, Kobayashi, H, Maruta, K, Mizusaki, J, Nitsuma, H, Ito, T, Yamamoto, K, Aoyagi, R, Suekane, T, Akaku, K, Hashida, T

    Tohoku University Press 2008年3月

  3. 機械工学便覧 基礎編α3 材料力学

    伊藤高敏他

    2005年4月25日

講演・口頭発表等 217

  1. Environmental impact of telework with direct uses of geothermal heat: A case study of Naruko area

    Suzuki, A, Hasegawa, R, Hienuki, S, Kubota, H, Ito, T

    47th Stanford Geothermal Workshop

  2. アフターコロナの働き方はこれだ!温泉地域テレワークによる環境負荷提言効果の検証

    鈴木杏奈, 長谷川諒, 稗貫峻一, 窪田ひろみ, 伊藤高敏

    第8回東北大学若手研究者アンサンブルワークショップ

  3. テレワークと温泉熱利用による環境負荷低減効果の評価:鳴子地域のケーススタディ

    長谷川諒, 鈴木杏奈, 伊藤高敏, 稗貫峻一, 窪田ひろみ

    日本地熱学会令和3年学術講演会

  4. 地殻応力にスケールされる微小地震クラウドの成長過程

    椋平祐輔, 伊藤高敏, 岡本京祐, 石橋琢也, 浅沼宏, 熊野裕介, 森谷祐一, Meihua Yang, Kangnan Yan, Yunhei Zuo, Justin Rubinstein, Markus O. Häring

    日本地熱学会令和3年学術講演会

  5. 注水によるせん断すべり挙動解明のための実験的研究

    青木晃司, 椋平祐輔, 伊藤高敏

    日本地熱学会令和3年学術講演会

  6. 大深度地熱井における地殻応力測定を目的とした大口径8-1/2”用二重ビットコアリングツールの開発,

    手塚和彦, 永嶋希望, 伊藤高敏, 小川浩司, 船戸明雄, 横山幸也

    日本地熱学会令和3年学術講演会

  7. 地熱井への適用を考慮した二重解放コア変形原理による地殻応力測定法の室内実験による検討

    伊藤高敏, 手塚和彦, 小川浩司, 船戸明雄, 横山幸也

    日本地熱学会令和3年学術講演会

  8. Topological data analysis for mass tracer transport in fracture networks

    Goto, K, Suzuki, A, Minto, J, Ito, T

    18th International Conference on Flow Dynamics

  9. Application of core-based inversion to reconstruct stress field in an underground geoscience laboratory

    Ma, X, Mukuhira, Y, Ito, T

    the 21st International Symposium on Advanced Fluid Information

  10. Understanding failure phenomena accelerated by machine learning for subsurface energy development

    Aoki, K, Mukuhira, Y, Naoi, M, Ito, T

    the 21st International Symposium on Advanced Fluid Information

  11. Numerical simulation of permeability development along closed fracture by methane hydrate dissociation

    Zhang, R, Ito, T, Komai, T, Sakamoto, Y, Tenma, N

    the 21st International Symposium on Advanced Fluid Information

  12. Detection of P-S travel time for Low SNR Event by particle motion analysis

    Jingyi, S, Mukuhira, Y, Nagata, T, Nonomura, T, Moriya, H, Ito, T

    the 14th SEGJ International Symposium

  13. Characteristic of Pore Pressure Migration Clarified by Multidisciplinary Microseismic Analysis

    Mukuhira, Y, Ito, T, Moriya, H, Asanuma, H, Häring, M. O

    World Geothermal Congress 2020+1 2021年7月6日

  14. Development and application of high stiffness fracturing systems for stress measurements corresponding to new standard in Japan

    Yokoyama, T, Funato, A, Ito, T, Ogawa, K, Nayuki, T

    55th US Rock Mechanics/Geomechanics Symposium

  15. Effect of system compliance on pressure-time curve at reopening and new standard in Japan

    Ito, T, Yokoyama, T

    55th US Rock Mechanics/Geomechanics Symposium

  16. A new method developed for rock stress measurement at deep depth in high temperature environment

    Ito, T, Kumazawa, A, Funato, A, Tezuka, K, Yokoyama, T

    World Geothermal Congress 2020+1 2021年6月15日

  17. メタンハイドレートの分解を利用したフラクチャー浸透性改良の数値シミュレーション

    張 溶昌, 伊藤高敏, 天満則夫

    2021 (令和3) 年度 資源・素材学会 東北支部 総会・春季大会 2021年6月9日

  18. Experimental study on fluid injection-induced fault slip

    Aoki, K, Mukuhira, Y, Ito, T

    JpGU Meeting 2021

  19. プロパントによる未固結砂層フラクチャー内の流動性保持に関する研究

    張 溶昌, 伊藤高敏, 駒井 武, 坂本靖英, 天満則夫

    第15 回岩の力学国内シンポジウム

  20. 二重解放コア変形原理による地殻応力測定法のため特殊ビット開発と実証

    手塚和彦, 小川浩司, 横山幸也, 船戸明雄, 伊藤高敏

    第15 回岩の力学国内シンポジウム

  21. In-situ crustal stress in inland Japan with application of DCDA method to rock core samples of seismic observation wells

    Omura, K, A. Funato, T. Ito

    American Geophysical Union (AGU) Fall Meeting 2020

  22. 微粒子を用いた砂層内フラクチャー伸展の制御技術とCTによる可視化実験

    伊藤高敏

    砂層型メタンハイドレートフォーラム 2020年12月16日

  23. 二重解放コアを用いた地殻応力測定法の研究開発 -小口径ツールの実証―

    手塚和彦, 伊藤高敏, 小川浩司, 横山幸也, 船戸明雄

    日本地熱学会令和2年学術講演会

  24. 主応力比情報を用いた微小地震の断層面解範囲絞り込み

    椋平祐輔, 伊藤高敏, 浅沼 宏, M.O. Häring

    日本地熱学会令和2年学術講演会

  25. A breakthrough in rock stress measurement applicable deep and high temperature environment 招待有り

    Ito, T, Kumazawa, A, Tezuka, K, Ogawa, K, Yokoyama, T, Funato, A

    International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application (CouFrac)

  26. ICDP DSeis計画:M5.5余震発生帯におけるコア変形法(DCDA)による空間応力変化の評価

    美間良大, 田所遼悟, 吉田 峻輔, 東 充也, 阪口健介, L. Bennie, M. Siyanda, 矢部康男, 船戸明雄, 伊藤高敏, D. Raymond, 小笠原 宏

    日本地震学会秋季大会

  27. 神岡鉱山における二重コアビットによる地殻応力測定法の検証

    手塚和彦, 山本俊也, 伊藤高敏, 小川浩司, 横山幸也, 船戸明雄

    石油技術協会令和2年度学術大会

  28. 注水に伴う断層の動的すべり発生メカニズムの検討

    伊藤高敏, 横山圭祐, 椋平祐輔

    石油技術協会令和2年度学術大会

  29. 地殻応力情報を用いた微小地震の断層面解限定

    椋平祐輔, 直井 誠, 森谷祐一, 伊藤高敏, 浅沼 宏, M.O. Häring

    石油技術協会令和2年度学術大会

  30. First application result of DCDA method to the rock core samples from underground geoscience laboratory

    Ma, X, Y. Mukuhira, T. Ito

    20th International Symposium on Advanced Fluid Information

  31. 岩石内の流れを推定するパーシステントホモロジー

    鈴木杏奈, 宮澤美幸, 大林一平, 平岡裕章, 伊藤高敏

    日本応用数理学会2020年度年会

  32. 流体圧刺激による断層すべり発生のメカニズムと対策 招待有り

    伊藤高敏, 横山佳祐, 熊澤明信, 手塚和彦, 小川浩司, 横山幸也, 船戸明雄

    資源・素材関係学協会合同秋季大会

  33. Estimating flow characteristics of 3D fracture network based on persistent homology

    Suzuki, A, M. Miyazawa, T. Ito, P. Kan

    InterPore2020

  34. Stress heterogeneity in the source region of the 2014 Orkney earthquake (M5.5), South Africa, estimated by ICDP-DSeis

    Yabe, Y, M. Kanematsu, M. Higashi, R. Tadokoro, S. Yoshida, K. Sugimura, H. Ogasawara, T. Ito, A. Funato, M. Ziegler, B. Liebenbeng, B. Watson, S. Mngadi, M. Manzi, R. Durrheim

    JpGU-AGU Joint Meeting 2020

  35. Estimation of focal mechanisms of more number of induced seismicity to understand fracture system in the geothermal reservoir

    Yan, K, M. Mukuhira, T. Ito, Y. Zuo, H. Asanuma, M.O. Häring

    JpGU-AGU Joint Meeting 2020

  36. Investigation of the physical link between the injection induced seismicity and information from borehole logging

    Mukuhira, Y, M. Ziegler, T. Ito, H. Asanuma, M.O. Häring

    JpGU-AGU Joint Meeting 2020

  37. Characterization of permeability based on topological data of fracture network

    Suzuki, A, M. Miyazawa, James Minto, T. Tsuji, T. Ito

    JpGU-AGU Joint Meeting 2020

  38. Experimental verification of the Dual Bit Coring method developed for stress measurement applicable in deep and high temperature environment

    Ito, T, A. Kumazawa, K. Tezuka, T. Yokoyama, K. Ogawa, A. Funato

    54th US Rock Mechanics/Geomechanics Symposium

  39. 地下3km以深の太古代泥質変成堆積岩中のランプロファイアー上で発生したM5.5地震の余震発生帯掘削調査

    小笠原宏, 矢部康男, 伊藤高敏, 船戸明雄, 廣野哲朗, 山本裕二, ICDP DSeis team

    日本材料学会第69回学術講演会

  40. The seismogenic zones of an M2.0-5.5 earthquakes successfully recovered in deep South African gold mines: the outcomes and the follow-up plan

    Ogasawara, H, B. Liebenberg, Y. Yabe, Y. Yokoyama, T. Hirono, D. Nisson, T.C. Onstott, T. Kieft, E. Cason, T. Wiersberg, M. Manzi, S. Mngadi, R. Durrheim, Y. Yamamoto, T. Ito, A. Funato, M. Ziegler, J. Mori, C. Dinske, the DSeis team

    European Geosciences Union (EGU) General Assembly 2020

  41. Stress state in the upper margin of aftershock zone of the 2014 Orkney earthquake (M.5.5), South Africa, estimated from analyses of drill cores and borehole breakout of ICDP-DSeis drillings

    Yabe, Y, M. Kanematsu, M. Higashi, R. Tadokoro, S. Yoshida, K. Sugimura, H. Ogasawara, T. Ito, A. Funato, M. Ziegler, B. Liebenbeng, B. Watson, S. Mngadi, M. Manzi, R. Durrheim

    European Geosciences Union (EGU) General Assembly 2020

  42. オイルサンド開発を⽬的とした間隙圧上昇によるせん断膨張と浸透性変化の検討

    楊 徳殻, 伊藤高敏, 柏原巧治, 内田 優

    資源・素材関係学協会合同春季大会

  43. Singular Behavior and Its Control of Hydraulic Fracture in Sands Verified in Laboratory Experiments with Aid of CT Scanner

    Ito, T., Yoshida, H., Mukuhira, Y., Yamamoto, K., Tsuchiya, Y.

    AGU fall meeting 2019 2019年12月9日

  44. Understanding of the physics of induced seismicity from natural fracture and in-situstress information from borehole logging

    Mukuhira, Y., Ziegler, M., Ito, T.

    AGU fall meeting 2019 2019年12月9日

  45. Stress state in the upper margin of aftershock zone of the 2014 Orkney earthqauke (M5.5), South Africa, measured from boring cores of ICDP-DSeis project

    31. Yabe, Y., Kanematsu, M., Higashi, R., Tadokoro, R., Yoshida, S., Sugimura, K., Ogasawara, H., Ito, T., Funato, A., Liebenberg, B., Watson, B., Mngadi, M., Manzi, M. and Durrheim, R.

    AGU fall meeting 2019 2019年12月9日

  46. Potential borehole observatory in the aftershock zone at about 3.5 km depth of a 2014 M5.5 sinistral earthquake that the ICDP DSeis project has probed

    Ogasawara, H., Onstotte, T.C., Kieft, T., Wiersberg, T., Zimmer, M., Yabe, Y., Durrheim, R., Manzi, M., Cason, E., Leibenberg, B., Ziegler, M., Hirono, T., Ito, T., Funato, A., Yamamoto, Y. and ICDP DSeis team

    AGU fall meeting 2019 2019年12月9日

  47. Consistency evaluation of three advanced stress measurement techniques upon Dual Core-bit Coring, Compact Conical-ended Borehole Overcoring and High Stiffness Hydraulic Fracturing at Kamioka mine, Japan

    Yokoyama, T., Ito, T., Tezuka, K. and Funato, A.

    AGU fall meeting 2019 2019年12月9日

  48. Practical application of the dual core-bit tool for drilling stress record cores to stress measurements at Kamioka mine, Japan

    Tezuka, K., Yamamoto, T., Ito, T., Yokoyama, T. and Funato, A.

    AGU fall meeting 2019 2019年12月9日

  49. A new method of rock stress measurements on stress record core obtained by the dual bit coring and its laboratory verification

    Kumazawa, A., Ito, T., Funato, A., Tezuka, K. and Yokoyama, T.

    AGU fall meeting 2019 2019年12月9日

  50. Introduction of natural fracture information to induced seismicity analysis

    Mukuhira, Y., Ziegler, M., Ito, T., Asanuma, H., Häring, M. O.

    YSRM2019 & REIF2019 2019年12月1日

  51. メタンハイドレート開発に関わる未固結地層破壊挙動の解明~フラクチャー・クリーンアウト現象の再現と可視化~

    伊藤高敏

    砂層型メタンハイドレートフォーラム 2019年12月3日

  52. 注水による断層すべりの発生機構に関するシミュレーション

    横山佳祐,椋平祐輔,伊藤高敏

    日本地熱学会令和元年学術講演会 2019年11月20日

  53. 地殻応力情報を用いた微小地震の断層面解範囲絞り込み

    椋平祐輔,直井 誠,M. C. Fehler, 森谷祐一,伊藤高敏,浅沼 宏,M.O. Häring

    日本地熱学会令和元年学術講演会 2019年11月20日

  54. Topological data analysis for estimating flow characteristics of 3D fracture network

    The 16th International Conference of Flow Dynamics 2019年11月6日

  55. Application of core-based inversion to reconstruct stress field in an underground geoscience laboratory

    Ma, X., Mukuhira, Y., Ito, T.

    19th International Symposium on Advanced Fluid Information 2019年11月6日

  56. メタンハイドレート開発に関わる未固結地層破壊挙動の解明~フラクチャー・クリーンアウト現象の再現と可視化~

    伊藤高敏

    JOGMEC-TRCウィーク 2019年10月28日

  57. irst field test of the dual core-bit tool for drilling stress record cores at kamioka mine, Japan

    Tezuka, K., Yamamoto, T., Ito, T., Yokoyama, T. and Funato, A.

    25th Formation Evaluation Symposium of Japan 2019年9月25日

  58. 二重コアリングで得られたコアを用いる地殻応力測定法の研究

    熊澤明信, 伊藤高敏,船戸明雄,手塚和彦,横山幸也

    資源素材学会秋季大会 2019年9月24日

  59. In-situ stress constraints on the focal mechanisms of induced seismicity

    Mukuhira, Y., Ito, T., Fehler, M. C., Naoi, M., Moriya, H., Asanuma, H., Häring, M. O.

    14th international congress on rock mechanics and rock engineering 2019年9月13日

  60. Development of stress record coring method for stress measurement

    Ito, T.

    Annual Meeting of ISRM Commission on Crustal Stress and Earthquake 2019年9月15日

  61. Effect of capillary force on performance of shale rock fracturing

    Liu, B., Suzuki, A. and Ito, T.

    53rd US Rock Mechanics / Geomechanics Symposium 2019年6月23日

  62. Experimental study of tip screenout fracturing by using CT scanner

    Ito, T., Yoshida, H., Yamamoto, K. and Tsuchiya, Y.

    53rd US Rock Mechanics/Geomechanics Symposium 2019年6月23日

  63. The 2019 overview of Drilling into Seismogenic zones of M2.0-5.5 earthquakes in South African gold mines (DSeis)

    Ogasawara, H., Liebenberg, B., Ziegler, M., Yabe, Y., Durrheim, R.J., Mngadi, S., Tau, S., Kaneki, S., Yokoyama, Y., Hirono, T., Onstott, T.C., Wiesberg, T., Zimmer, M., Kujawa, C., Conze, R., Aswegen, G.V., Wechsler, N. and ICDP DSeis team

    9th Int. Conf. on Deep Mining 2019年6月24日

  64. In-situ stress around earthquake source faults in and beneath South African deep gold mines

    Yabe, Y., Abe, S., Ito, T., Ishida, A., Sugimura, K., Kanematsu, M., Higashi, M., Tadokoro, R. and Ogasawara, H.

    9th Int. Conf. on Deep Mining 2019年6月24日

  65. A Novel Method to Estimate Fracture Permeability: Combining microseismic observational data and reservoir engineering model

    Yang, M., Mukuhira, Y., and Ito, T.

    JpGU meeting 2019 2019年5月26日

  66. Constraint of focal mechanisms of induced seismicity by using misfit angles based on known in-situ stress

    Mukuhira, Y., Naoi, M., Fehler, M., Moriya, H., Ito, T., Asanuma, H., and Häring, M.O.

    JpGU meeting 2019 2019年5月26日

  67. Topological characterization of 3D printing fracture networks

    Suzuki, A., Miyazawa, M., Konno, M. and Ito, T.

    JpGU meeting 2019 2019年5月26日

  68. Estimation of fracture apertures in fractured porous media by nano-/microparticles

    Suzuki, A., Cui, J., Zhang, Y., Li, K., Horne, R.N. and Ito, T.

    JpGU meeting 2019 2019年5月26日

  69. Causality between induced seismicity b-value reduction and stress state of existing fractures

    Mukuhira, Y., Fehler, M., Ito, T., Asanuma, H., and Häring, M.O.

    JpGU meeting 2019 2019年5月26日

  70. Comparison of stress field change around a fault by dynamic fault rupture simulation using 3D-FEM

    Iwata, N., Kiyota, R., Aydan, O., Ito, T. and Miura, F.

    Rock Dynamics Summit 2019年5月7日

  71. Effects of fault geometry and subsurface structure model on the strong motion and surface rupture induced by the 2014 Kamishiro Fault Nagano Earthquake

    Iwata, N., Kiyota, R., Aydan, Ö., Ito, T. and Miura, F.

    Rock Dynamics Summit 2019年5月7日

  72. Spatial variation in stress in seismogenic zones in South African gold mines

    Ogasawara, H., Ishida, A., Sugimura, K., Yabe, Y., Abe, S., Ito, T., Funato, A., Kato, H., Liebenberg, B., Hofmann, G., Scheepers, L., Durrheim, R.J. and The SATREPS & DSeis teams,

    Rock Dynamics Summit 2019年5月7日

  73. Rock stresses around actual faults measured by using a hydraulic fracturing technique

    Yokoyama, T., Lin, W., Danjo, T. and Ito, T.

    Rock Dynamics Summit 2019年5月7日

  74. Experimental study on hydraulic fracturing in unconsolidated sands for its application to methane hydrate development

    Ito, T. and Tenma, N.

    AAPG Geosciences Technology Workshop: Gas Hydrates – From Potential Geohazard to Carbon-Efficient Fuel? 2019年4月15日

  75. An overview of the completed ICDP project, Drilling into Seismogenic zones of M2.0-5.5 earthquakes in South African gold mines (DSeis)

    Ogasawara, H., Liebenberg, B.,Yabe, Y., Durrheim, R., Ziegler, M., Manzi, M., Mngadi, S., Onstott, T., Funato, A., Ito, T., Hirono, T., Kaneki, S., Yokoyama, Y., Yamamoto, Y. and ICDP DSeis team

    EGU 2019年4月7日

  76. In-situ stress around earthquake source faults in and beneath South African deep gold mines

    Yabe, Y., Abe, S., Ito, T., Ishida, A., Sugimura, K., Kanematsu, M., Higashi, M., Tadokoro, R., Ogasawara, H., Funato, A., Kato, H., Watson, B., Mngadi and Durrheim, R.

    EGU 2019年4月7日

  77. 断層面の形状や地質構造の違いによる強震動と断層変位の比較:神城断層地震を事例として

    岩田 直樹, 清田 亮二, 藍檀 オメル, 伊藤 高敏, 三浦 房紀

    第46回岩盤力学に関するシンポジウム 2019年1月12日

  78. 3次元有限要素法による動的破壊シミュレーションに基づく断層パラメータの 違いによる断層周辺の応力変化

    岩田 直樹, 清田 亮二, 藍檀 オメル, 伊藤 高敏, 三浦 房紀

    第46回岩盤力学に関するシンポジウム 2019年1月12日

  79. Topological data analysis and 3D printing technologies for understanding of flow in fracture networks

    Suzuki, A, Miyazawa, M, Ito, T

    American Geophysical Union Fall Meeting 2018 2018年12月10日

  80. Constraint of focal mechanisms of induced seismicity by analyzing consistency of slip vector using in-situ stress

    Mukuhira, Y, Fuse, K, Naoi, M, Ito, T, Fehler, M.C, Moriya, H, Asanuma. H, Haring, M.O

    American Geophysical Union Fall Meeting 2018 2018年12月10日

  81. き裂システムに対する注水時の間隙水圧伝播 国際会議

    椋平祐輔, 森谷祐一, 伊藤高敏, 浅沼 宏, Haring Marcus

    日本地熱学会平成30年学術講演会 2018年11月13日

  82. A Numerical Study on Permeability enhancement caused by pore-pressure driven shear dilation for oil sands development

    Watanabe, M, Ito, T, Tamagawa, T, Tezuka, K

    International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application 2018年11月12日

  83. Numerical study to learn different fracturing performance induced by supercritical CO2 and aqueous fluids

    Liu, B, Suzuki, A, Ito, T

    International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application 2018年11月12日

  84. Estimation of crack width in porous media by nano/micro particles

    Cui, J, Suzuki, A, Ito, T

    International Conference on Coupled Processes in Fractured Geological Media: Observation, Modeling, and Application 2018年11月12日

  85. Introduction of in-situ stress information from borehole logging to source characterization of microseismic events

    Mukuhira, Y, Fuse, K, Naoi, M, Ito, T, Fehler, M.C, Moriya, H, Asanuma. H, Haring, M.O

    The 13th SEGJ International Symposium 2018年11月12日

  86. A new flow model based on Pore Scale Netwrok Method for supercritical CO2 fracturing

    Liu, B, Suzuki, A, Ito, T

    The 15th International Conference on Flow Dynamics 2018年11月7日

  87. Analysis of rock fracture pattern and fluid flow by persistent homology

    The 15th International Conference on Flow Dynamics 2018年11月7日

  88. Estimation of crack width in porous media by nano/micro particles

    Cui, J, Suzuki, A, Uehara, S, Shirasu, K, Ito, T

    The 15th International Conference on Flow Dynamics 2018年11月7日

  89. Dependency of the injection induced seismicity b-value on the stress state of existing fractures

    Mukuhira, Y, Fehler, M, Ito, T, Asanuma, H, Haring, M.O

    Banff 2018 International Induced Seismicity Workshop 2018年10月24日

  90. 誘発地震b値のせん断応力依存性 国際会議

    椋平祐輔, 伊藤高敏, Fehler, M.C, 浅沼 宏, Haring, M.O

    日本地震学会2018年度秋季大会 2018年10月9日

  91. 南アフリカ大深度金鉱山で発生したMw2.2の地震の震源域の応力場 国際会議

    矢部康男, 阿部周平, 小笠原宏, 伊藤高敏, 船戸明雄, Drurheim, R, Yilmaz, H, Hofmann, G

    日本地震学会2018年度秋季大会 2018年10月9日

  92. ICDP 南アフリカ金鉱山 地震発生場掘削の完了 国際会議

    小笠原宏, 矢部康男, 伊藤高敏, DSeisチーム(ICDP

    日本地震学会2018年度秋季大会 2018年10月9日

  93. 主応力比の大きい地盤応力状態下における水圧破砕試験でのき裂挙動 国際会議

    横山幸也, 坂口清敏, 伊藤高敏

    資源素材学会秋季大会 2018年9月10日

  94. 数値シミュレーションによるフラクチャー分岐特性の考察 国際会議

    伊藤高敏

    資源素材学会秋季大会 2018年9月10日

  95. 数値シミュレーションと組み合わせた構造解析による蛇紋岩の形成メカニズム推定 国際会議

    宮澤美幸, 鈴木杏奈, 岡本敦, 清水浩之, 大林一平, 平岡裕章, 伊藤高敏

    日本地質学会第125年学術大会 2018年9月5日

  96. 大深度南アフリカ金鉱山の地震発生場での岩盤応力測定 国際会議

    小笠原宏, 石田亮壮, 小笠原宏幸, 杉村幸佑, 野田 拓, 阿部周二, 矢部康男, 加藤春實, 伊藤高敏, 船戸明雄

    第53回地盤工学研究発表会 2018年7月24日

  97. エネルギー資源開発のための注水による断層すべりに及ぼす岩盤応力の影響 国際会議

    伊藤高敏, 横山圭祐

    第53回地盤工学研究発表会 2018年7月24日

  98. Current Status of Research and Development on Supercritical Geothermal Resources in Japan

    Asanuma, H, Mogi, T, Tsuchiya, N, Watanabe, N, Naganawa, S, Ogawa, Y, Fujimitsu, Y, Kajiwara, T, Osato, K, Shimada, K, Horimoto, S, Sato, T, Ito, T, Yamada, S, Kondo, S, Watanabe, K, Gotoh, Y, Okada, H, Yoshida, Y, Nagasawa, Y, Koyama, A

    Grand Renewable Energy 2018 International Conference and Exhibition 2018年7月17日

  99. 間隙圧上昇によるシェアダイレーションと浸透性変化挙動の数値シミュレーション 国際会議

    渡辺雅大, 伊藤高敏, 玉川哲也, 手塚和彦

    平成30年度石油技術協会春季講演会 2018年6月13日

  100. CT スキャナを用いた室内実験によるスクリーンアウト現象の検討 国際会議

    吉田日向, 伊藤高敏, 山本晃司, 土屋慶洋

    平成30年度石油技術協会春季講演会 2018年6月13日

  101. タンハイドレート開発を目的とした未固結砂層のフラクチャリングに関する基礎研究 国際会議 招待有り

    伊藤高敏, 天満則夫

    平成30年度石油技術協会春季講演会 2018年6月13日

  102. 既存岩石コアへコア変形法を適用した原位置地殻応力測定 国際会議

    小村健太郎, 林 為人, 伊藤高敏, 船戸明雄

    日本地球惑星科学連合2018大会 2018年5月20日

  103. 個別要素法シミュレーションによるせん断帯き裂構造に及ぼす応力状態の影響の解析 国際会議

    布施知正, 岡本 敦, 伊藤高敏, 清水浩之

    日本地球惑星科学連合2018大会 2018年5月20日

  104. Analysis of rock fracture patterns by Persistent Himology

    Suzuki, A, Miyazawa, M, Okamoto, A, Shimizu, H, Hirooka, Y, Obayashi, I, Ito, T

    Japan Geoscience Union Meeting 2018年5月20日

  105. The status of on-going drilling into seismogenic zones of M2.0 - M5.5 earthquakes from deep South African gold mines (DSeis)

    Ogasawa, H, Durrheim, R, Manzi, M, Yabe, Y, Onstott, T, Ziegler, M, Ito, T, Liebenberg, B, Grobbelaar, M, Ellsworth, W, Boettcher, M, Wechsler, W, Aswegen, G, Somala, S.N, the ICDP DSeis team

    European Geosciences Union General Assembly 2018 2018年4月8日

  106. Core and borehole logging and stress measurements of a 817 m long borehole drilled from 2.9 km depth toward the Moab Khotsong 2014 M5.5 aftershock zone (ICDP DSeis project in South Africa)

    Ziegler, M, Rickenbacher, M, Berset, N, Liebenberg, B, Ishida, A, Sugimura, K, Noda, T, Ogasawara, H, Mngadi, S, Durrheim, R, Ito, T, Funato, A, the ICDP DSeis team

    European Geosciences Union General Assembly 2018 2018年4月8日

  107. コア変形法(DCDA)における改良ビットの効果について 国際会議

    船戸明雄, 伊藤高敏

    野島プロジェクト研究成果報告会 2018年3月25日

  108. 南アフリカ金鉱山の地震発生場における応力・強度・ひずみ変化の現位置計測 国際会議

    小笠原宏, 石田亮壮, 阿部周平, 矢部康男, 伊藤高敏, 船戸明雄, 小笠原宏幸, 安富達就, 杉村幸佑, 野田 拓, DSeis研究チーム

    「災害の軽減に貢献するための地震火山観測研究計画」成果報告 2018年3月14日

  109. Constraining of focal mechanisms of induced seismicity using borehole logging information

    Mukuhira, Y, Fuse, K, Naoi, K, Fehler, M, Ito, T, Moriya, H, Asanuma, H, Haring, M.O

    The 43rd Stanford Geothermal Workshop 2018年2月12日

  110. 3次元有限要素法による2014年神城断層地震の地震動再現解析 国際会議

    岩田 直樹, 清田 亮二, 足立 光, 藍檀 オメル, 伊藤 高敏, 三浦 房紀

    第45回岩盤力学に関するシンポジウム 2018年1月15日

  111. X線CTスキャナを利用した水圧破砕き裂伸展挙動の研究

    長野優羽

    第14回岩の力学国内シンポジウム 2017年1月10日

  112. Determination of Focal Mechanism of Induced Seismicity by using Regional Stress Data 国際会議

    AGU Fall Meeting 2016年12月

  113. Estimate of the Stress State in an Earthquake Source Region in a South African Deep Gold Mine by Diametrical Core Deformation Analysis (DCDA) 国際会議

    AGU Fall Meeting 2016年12月

  114. Investigation into the Physical Process of Sand Production in Unconsolidated Sands by Laboratory Experiments using X-ray CT for Methane Hydrate Development 国際会議

    AGU Fall Meeting 2016年12月

  115. Propagation Speed of Pore Pressure throughout Permeable Fracture during Hydraulic Stimulation 国際会議

    AGU Fall Meeting 2016年12月

  116. 個別要素法による未固結地層フラクチャリング挙動に影響を与える要因の検討

    第8回メタンハイドレート総合シンポジウム (CSMH-8) 2016年12月

  117. Effect of Shear Dilation on Fault Slip Induced by Fluid Injection 国際会議

    The 13th International Conference on Flow Dynamics (ICFD2016) 2016年10月

  118. Investigation of Distinct Element Modeling to Represent Hydraulic Fracturing Behavior in Unconsolidated Sand 国際会議

    The 13th International Conference on Flow Dynamics (ICFD2016) 2016年10月

  119. 主応力比の大きい岩盤応力下における水圧破砕試験でのき裂の再開口と閉口挙動に関する考察

    第51回地盤工学研究発表会 2016年9月

  120. 水圧破砕法による初期地圧測定方法の基準化について

    第51回地盤工学研究発表会 2016年9月

  121. 地震発生に伴う震源断層近傍の応力変化

    第51回地盤工学研究発表会 2016年9月

  122. 地熱貯留層の力学と応力

    地熱協会技術部講演会 2016年7月11日

  123. Stress State Analysis of Fault Plane of Large Induced Seismicity 国際会議

    The 50th US Rock Mechanics / Geomechanics Symposium 2016年6月

  124. A proposed Method and Its Application of Deep Stress Measurements 国際会議

    Japan Geoscience Union Meeting 2016 2016年5月22日

  125. Development of the Deep Rock Stress Tester, DRST 国際会議

    The 7th International Symposium on In-situ Rock Stress 2016年5月

  126. Estimate of the Stress State of Earthquake Source Region in a South African Deep Gold Mining by Diametrical Core Deformation Analysis (DCDA) 国際会議

    Japan Geoscience Union Meeting 2016 2016年5月

  127. Laboratory Study of Sand Production in Unconsolidated Sands by Using X-ray CT for Methane Hydrate Development 国際会議

    SPE Workshop“Sand Management Workshop” 2016年4月25日

  128. Causality between Expansion of Seismic Cloud and Maximum Magnitude of Induced Seismicity in Geothermal Feld 国際会議

    EGU General Assembly 2016 2016年4月

  129. Drilling into Seismogenic Zones of M2.0-M5.5 Earthquakes in Deep South African Gold Mines (DSeis) 国際会議

    EGU General Assembly 2016 2016年4月

  130. 圧力変化を利用したCO2地中貯留層からの漏洩防止法の検討

    資源・素材学会 平成28(2016)年度 春季大会 2016年3月28日

  131. 南アフリカ金鉱山の地震発生場における応力・強度・ひずみ変化の現位置計測

    平成27年度「災害軽減に貢献するための地震火山観測研究」成果報告シンポジウム 2016年3月

  132. 個別要素法による特異な未固結地層フラクチャリング挙動再現の試み

    第7回メタンハイドレート総合シンポジウムCSMH-7 2015年12月2日

  133. 未固結層からの出砂過程の室内実験による可視化観察

    第7回メタンハイドレート総合シンポジウムCSMH-7 2015年12月2日

  134. 未固結地層の力学特性および拘束圧がフラクチャリング挙動に与える影響に対する個別要素法解析

    資源・素材学会東北支部平成27年度秋季大会研究発表講演会 2015年11月16日

  135. Hydro fracturing method and stress estimation by analyzing core shape 国際会議

    The ICDP DSeis Workshop“Drilling into Seismogenic Zones of M2.0-5.5 earthquakes in South African gold mines 2015年11月1日

  136. How the information of rock stress is useful for subsurface development and how it is measured at deep depths 国際会議

    The 21st Formation Evaluation Symposium of Japan 2015年10月13日

  137. 「Slip-able area」の概念に基づく水圧刺激時の誘発地震リスクアセスメント法の提案

    日本地熱学会平成27年学術講演会 2015年10月

  138. DEM Simulation for the Evaluation of Fracture Toughness during Hydraulic Fracturing 国際会議

    The Twelfth International Conference on Flow Dynamics ICFD2015 2015年10月

  139. Numerical Modeling of Fault Shear Slip Induced by Fluid Injection 国際会議

    The Twelfth International Conference on Flow Dynamics ICFD2015 2015年10月

  140. 南アフリカ大深度金鉱山での地震被害低減のための震源至近距離観測研究 – SATREPS等6カ年の活動のまとめ –

    日本地震学会2015年度秋季大会 2015年10月

  141. 注水による断層すべりの数値シミュレーション

    平成27年度資源・素材関係学協会合同秋季大会 2015年9月10日

  142. 個別要素法によるフラクチャリングシミュレーションにおける破壊じん性値評価手法の開発

    平成27年度資源・素材関係学協会合同秋季大会 2015年9月8日

  143. メタンハイドレート開発を目的とした未固結地層におけるフラクチャー挙動の実験的研究

    第50回地盤工学研究発表会 2015年9月2日

  144. Development of Experimental Apparatus for Real-time Observation of Hydraulic Fracture in Unconsolidated Sands by X-ray CT Method 国際会議

    School of Civil and Environmental Engineering, Georgia Institute of Technology 2015年8月4日

  145. X線CT を利用した未固結砂層の破壊と出砂の室内実験

    平成27 年度石油技術協会春季講演 2015年6月11日

  146. 石油傾斜井のkm 級深度における原位置の地殻応力評価へのコア変形法の適用

    平成27 年度石油技術協会春季講演 2015年6月11日

  147. Development of Experimental Apparatus for Real-time Observation of Hydraulic Fracture in Unconsolidated Sands by X-ray CT method 国際会議

    49th US Rock Mechanics Geomechanics Symposium 2015年6月

  148. 不均質構造で生じる岩石内部残留応力モデル

    日本材料学会第64期学術講演会 2015年5月23日

  149. 粒状体個別要素法による既存き裂を考慮した岩盤フラクチャリングのシミュレーション

    日本材料学会第64期学術講演会 2015年5月23日

  150. 供試体力学物性が未固結堆積層水圧破砕に及ぼす影響に関する個別要素法解析

    第6回メタンハイドレート総合シンポジウム 2014年12月3日

  151. 模擬未固結地層内フラクチャー伸展挙動の可視化手法の開発

    第6回メタンハイドレート総合シンポジウム 2014年12月3日

  152. Estimation of the Cumulative Fault Area Under Critical State Based on Microseismic Dataset at Hydraulic Stimulation for Seismic Risk Assessment 国際会議

    2014 AGU Fall Meeting 2014年12月

  153. A New Concept for Measuring Rock Stress at Depth Using a Core Obtained by Drilling 国際会議

    The eleventh International Conference on Flow Dynamics (ICFD2014) 2014年10月

  154. Comprehensive Evaluation of the Initial Rock Stress Carried Out as Part of a 2000m All Core Borehole Investigation 国際会議

    2014 ISRM International Symposium - the 8th Asian Rock Mechanics Symposium (ARMS8) 2014年10月

  155. Hydro-thermal-mechanical Coupled Simulation of Fluid Flow in Fracture at Depths for Geothermal Development 国際会議

    The eleventh International Conference on Flow Dynamics (ICFD2014) 2014年10月

  156. Real-time Observation of Hydraulic Fracture Growth in Soft Rocks under Confining Stress Using X-ray CT 国際会議

    2014 ISRM International Symposium - the 8th Asian Rock Mechanics Symposium (ARMS8) 2014年10月

  157. 封圧を受ける岩体の熱収縮による単一き裂の開口挙動

    日本地熱学会平成26年学術講演会 2014年10月

  158. Flow-coupled DEM modeling for hydraulic fracturing in unconsolidated sands 国際会議

    14th International Conference of the International Association for Computer Methods and Advances in Geomechanics (14th ICIACMAG) 2014年9月

  159. WG13(水圧破砕法)基準化委員会の方向性

    第49回地盤工学研究発表会 2014年7月15日

  160. 熊野海盆における大水深海底地層での水圧破砕地殻応力評価

    第49回地盤工学研究発表会 2014年7月15日

  161. 弾性異方性を考慮したコア変形モデル

    資源・素材学会東北支部平成26年度春季大会 2014年6月17日

  162. Laboratory Study for Pore Water Effect on Hydraulicallyinduced Fracture Behavior in Unconsolidated Sands 国際会議

    48th US Rock Mechanics Geomechanics Symposium 2014年6月4日

  163. Flow-coupled DEM simulation for hydraulic fracturing in pre-fractured rock 国際会議

    48th US Rock Mechanics Geomechanics Symposium 2014年6月2日

  164. 水圧刺激時の微小地震データに基づく破壊可能な断層面積 ”Slip-able area” 評価の試み

    日本地球惑星科学連合2014年大会 2014年5月2日

  165. 低温水流入に伴うき裂開口幅変化の数値解析

    日本地球惑星科学連合2014年大会 2014年5月2日

  166. メタンハイドレートと地熱と日本

    平成25年度触媒学会東北地区講演会「化石燃料を上手に使う! ~ポスト原発のエネルギー資源~」 2013年9月17日

  167. Development of Unconsolidated Sand Model Using Distinct Element Method for Hydraulic Fracturing 国際会議

    6th Int. Symposium on In-situ Rock Stress 2013年8月20日

  168. Diametrical Core Deformation Analysis (DCDA) – Measuring Device and Laboratory Verification - 国際会議

    6th Int. Symposium on In-situ Rock Stress 2013年8月20日

  169. Distinct Element Analysis of the Effect of Brittleness Index in Hydraulic Fracturing 国際会議

    6th Int. Symposium on In-situ Rock Stress 2013年8月20日

  170. Experiments to Investigate Effects of the Intermediate Principal Stress on the Borehole Breakout Development 国際会議

    6th Int. Symposium on In-situ Rock Stress 2013年8月20日

  171. Hydraulic Fracturing Behavior in Soft Rocks under Confining Stresses Observed by X-ray CT Method 国際会議

    6th Int. Symposium on In-situ Rock Stress 2013年8月20日

  172. Systematic Approach for Initial Rock Stress Estimation Using Borehole and Core Sample in a Deep Geological Location 国際会議

    6th Int. Symposium on In-situ Rock Stress 2013年8月20日

  173. Difficulties and Possible Solutions for Deep Stress Measurements 国際会議

    6th Int. Symposium on In-situ Rock Stress 2013年8月20日

  174. Distinct Element Analysis for Hydraulic Fracturing in Shale –Effect of Brittleness on the Fracture Propagation - 国際会議

    47th US Rock Mechanics / Geomechanics Symp. 2013年6月23日

  175. Experimental Study of Hydraulic Fracturing in Unconsolidated Sands Using X-ray CT Method 国際会議

    47th US Rock Mechanics / Geomechanics Symp. 2013年6月23日

  176. Development of Unconsolidated Sand Model Using Distinct Element Method and Calibration of Micro Parameters for Hydraulic Fracturing

    メタンハイドレート総合シンポジウムCSMH-4 2012年12月

  177. 延性帯EGSの岩石力学

    日本地熱学会平成24年度学術講演会 2012年10月

  178. Numerical Simulation of Cavity Expansion in Unconsolidated Sand Using Distinct Element Method

    2012年資源素材学会秋季大会 2012年9月

  179. CO2 貯留層からの漏洩修復法を検証するためのX線CT法による室内実験

    2012年資源素材学会秋季大会 2012年9月

  180. 破砕流体の浸透を伴う未固結地層フラクチャリング挙動のX線CT法による検討

    石油技術協会2012年春季大会 2012年6月

  181. 微小地震に基づく流体移動の評価法と地熱開発への応用

    日本地球惑星科学連合大会2012 2012年5月20日

  182. Stress State at the Expedition 319 Drilling Site Estimated from Hydrofracturing Data and Core Deformation Taking account of the System Compliance Effect 国際会議

    International Conference on a New Perspective of Great Earthquake along Subduction Zone 2012年2月28日

  183. Laboratory Verification of the Core Deformation Method Using Specimens Simulating the Rock at the c0009 Site 国際会議

    JPG International Conference on a New Perspective of Great Earthquakes along Subduction Zones in KOCHI 2012年2月

  184. Determination of Stress State in Deep Subsea Formation by Combination of Hydrofracturing Test and Core Analysis: A Case Study in the Integrated Ocean Drilling Program (IODP) Expedition 319 国際会議

    AGU Fall Meeting 2010年12月13日

  185. フラクチャリングによる未固結地層応力評価法の検討

    第2回メタンハイドレート総合シンポジウム 2010年12月2日

  186. 微小地震に基づく貯留層内の圧力伝播挙動評価方の客観性向上に関する研究

    日本地熱学会22年度学術講演会 2010年11月26日

  187. Laboratory Study on Hydraulic Fracturing in Unconsolidated Sands 国際会議

    International Symposium on Methane Hydrate Resources from Mallik to Nankai Trough 2010年11月17日

  188. 堆積軟岩層を対象としたフラクチャリング挙動の可視化に関する研究

    JOGMEC-TRCウィーク2010 2010年11月8日

  189. Deep Rock Stress Measurement by Hydraulic Fracturing Method Taking Account of System Compliance Effect 国際会議

    The 5th International Symposium of In-situ Rock Stress 2010年8月25日

  190. Measurement of Pressure and Flow Distribution in Fractured Geothermal Reservoirs at Few Km Deep 国際会議

    G-COE Symposium 2010 Dynamic Earth and Heterogeneous Structure 2010年7月15日

  191. CO2地中貯留層からの原位置反応法による漏洩修復と数値シミュレーションによる検討

    平成22年度石油技術協会春季講演会 2010年6月9日

  192. 未固結地層フラクチャリング模擬実験のX線CTによる可視化

    平成22年度石油技術協会春季講演会 2010年6月9日

  193. 大水深海底下の地層を対象にしたフラクチャリング技術

    資源・素材学会平成22年度春季大会 2010年4月1日

  194. Proposed Concept of In-situ Reaction Barrier to Remedy Leakage from Reservoirs of Geological CO2 Storage 国際会議

    The 2nd International Symposium of Experimental-Integrated Computational Chemistry on Multiscale Fluidics 2010年2月24日

  195. 未固結地層フラクチャリング挙動解明のための実験的アプローチ

    第1回メタンハイドレート総合シンポジウム 2010年2月16日

  196. A Preliminary Result of Stress Orientation Obtained from Drilling Induced Fractures and Borehole Breakouts at Site C0009 of Expedition 319, NanTroSEIZE 国際会議

    EOS Trans. AGU, Fall Meet. Suppl., 2009年12月

  197. Downhole Hydrologic Testing in the Kumano Basin and Underlying Sediments: Results from NanTroSEIZE Expedition 319 国際会議

    EOS Trans. AGU, Fall Meet. Suppl., 2009年12月

  198. Hydraulic Fracture Measurements at Site C0009 of IODP Expedition 319, NanTroSEIZE 国際会議

    EOS Trans. AGU, Fall Meet. Suppl., 2009年12月

  199. In Situ Stress and Deformation Patterns across the Nankai Kumano Basin and Forearc: Results from IODP Expedition 319 国際会議

    EOS Trans. AGU, Fall Meet. Suppl., 2009年12月

  200. Stress and Pore Pressure Measurement in IODP Riser Drilling: An Example from Expedition 319, Kumano Basin offshore SW Honshu, Japan 国際会議

    EOS Trans. AGU, Fall Meet. Suppl., 2009年12月

  201. NanTroSEIZE第319次航海におけるライザー掘削孔でのMDT応力試験

    日本地震学会2009年秋季大会 2009年10月

  202. NanTroSEIZE第319次航海におけるライザー掘削孔でのMDT水理試験

    日本地震学会2009年秋季大会 2009年10月

  203. Outline of the In-situ Hydraulic Tests Using MDT Tool at 2.7 – 3.6 km below Sea Level in the First Riser Hole on the NanTroSEIZE Operation 国際会議

    the 15th Formation Evaluation Symposium of Japan 2009年9月

  204. Outline of the In-situ Stress Tests Using MDT Tool at 2.7 – 3.6 km below Sea Level in the First Riser Hole on the NanTroSEIZE Operation 国際会議

    the 15th Formation Evaluation Symposium of Japan 2009年9月

  205. Overview of NanTroSEIZE Rise Logging: Operational Planning and Reality 国際会議

    the 15th Formation Evaluation Symposium of Japan 2009年9月

  206. キロメートル級深度における地殻応力計測の課題と解決策

    日本資源素材学会秋季大会 2009年9月

  207. Laboratory Test of Hydraulic Fracturing in Unconsolidated Deformable Rocks 国際会議

    4th Biot Conf. on Poromechanics 2009年6月

  208. 未固結砂層の水圧破砕挙動を模擬する室内実験

    平成21年度石油技術協会春季講演会 2009年6月

  209. CO2地中貯留層からの漏洩修復法の検討

    日本地球惑星科学連合2009年大会 2009年5月

  210. 微小地震による流路構造評価法の高度化

    藤村修一郎, 伊藤高敏, 海江田秀志

    日本地熱学会平成19年度学術講演会 2007年11月28日

  211. 未固結層に対するフラクチャリング室内実験

    五十嵐哲, 伊藤高敏, 鈴木清史, 長久保定雄, 松澤真樹, 山本晃司

    平成19年度石油技術協会春季講演会 2007年6月5日

  212. AEによる貯留層内圧力と流路構造評価−勇払油ガス田でのケーススタディ−

    伊藤高敏, 藤村修一郎, 林一夫, 手塚和彦

    平成19年度石油技術協会春季講演会 2007年6月5日

  213. き裂面加熱に伴う周囲岩体の熱膨張によるき裂内流動性変化の室内実験による検討

    伊藤高敏, 関根孝太郎, 山本晃司, 伊藤久男, 小村健太朗, 加藤春實, 田中博

    日本地球惑星科学連合2007年大会 2007年5月19日

  214. 最大応力計測問題を解決する高剛性型水破砕地殻応力計測法(BABHY方式)の開発

    伊藤高敏, 関根孝太郎, 伊藤久男, 小村健太朗, 加藤春實, 田中博

    日本材料学会第56期学術講演会 2007年5月19日

  215. 松代町におけるBABHY式水圧破砕法による地殻応力計測試験

    伊藤高敏, 関根孝太郎, 山本晃司, 伊藤久男, 小村健太朗, 加藤春實, 田中博

    資源・素材学会平成19年度春季大会 2007年3月29日

  216. 大深度地殻応力計測を目的としたBABHY式水圧破砕法とその実用化

    伊藤高敏, 伊藤久男, 小村健太朗, 田中博, 加藤春實, 狩野嘉昭

    第37回岩盤力学に関するシンポジウム 2007年1月10日

  217. Spatial variation in stress state in the source region of Orkeny earthqauke (M5.5) based on analyses of the ICDP-DSeis borehole cores

    Yabe, Y., Ishida, A., Sugimura, K., Kanematsu, M., Higashi, M., Yoshida, S., Ito, T., Funato, A., Watson, B., Durrheim, R., Liebenberg, B. and Ogasawara, H.

    JpGU meeting 2019 2019年5月26日

︎全件表示 ︎最初の5件までを表示

産業財産権 2

  1. 地殻応力測定方法

    伊藤 高敏, 玉川 哲也

    特許第6883811号

    産業財産権の種類: 特許権

  2. 地殻応力測定法

    伊藤高敏, 手塚和彦, 玉川哲也

    特許第6332653号

    産業財産権の種類: 特許権

共同研究・競争的資金等の研究課題 31

  1. 既存コアとコア変形法による東北・北海道の地殻応力マップの生成と地熱開発への応用

    伊藤 高敏

    2021年4月1日 ~ 2024年3月31日

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    JOGMEC((独)石油天然ガス・金属鉱物資源機構)は、地熱資源ポテンシャルの評価を目的とする調査を東北・北海道で2017年から実施しており、ヒートホールと呼ばれる調査井を深度1000m程度まで掘削して全深度のコアが採取されている。そこでJOGMECと交渉の上、東北大学に近い八幡平地域のヒートホール(A井と呼ぶ)のコアを一昨年に入手した。続いて昨年には、同地域の別の2カ所で掘削されたヒートホール(BおよびC井と呼ぶ)の深度約1000~1400mの範囲で採取されたコアを入手した。これらのコアの直径分布を測定し、その結果とコア変形法によってコア直交面内の地殻応力差を評価する作業を進めている。また、後者のBおよびC井では、一部の深度でディスキングつまりコアが直径方向に割れて薄い円盤になる現象が起こっていた。この現象は地殻応力状態を表す1つの指標とされ、坑井軸方向と直交方向の地殻応力差が極端に大きい場合に起こると理解されている。しかし、1000mを越える大きな深度でディスキングが起こる原因は明らかではない。そこで、ディスキング現象とコア変形情報を組み合わせることで地殻応力状態を評価する解析を進めている。一方、コア形状から地殻応力差を求める際には、コアのヤング率が必要となる。その測定を行うには、コアから円柱試験片を切り出し、それで一軸圧縮試験を行うという煩雑で時間を要する作業が必要となる。また、このことが原理的には非常にシンプルなコア変形法を煩雑にする要因となっている。そこで、より簡便にコアのヤング率を測定する方法を考案して検証した。これによれば、コア表面にひずみゲージを貼り付けるだけで、非破壊で測定することが可能となる。今後は、それを実行するための測定システムを構築し、これまで入手したコアに適用していく。

  2. エネルギー開発リスクとなる断層活動性の定量評価に関する研究

    伊藤 高敏

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    2016年4月1日 ~ 2020年3月31日

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    エネルギー資源開発で実施されるフラクチャリングにおいて、ボーリング孔を通して地下岩体に負荷した流体圧が、地表で人が感じる程度に大きな地震を発生させる原因を数値シミュレーションに基づいて考察した。その結果、負荷した流体圧が付近の既存断層に及ぶと、MPaオーダーの変化でもkm2オーダーの広い範囲が瞬間的にすべり得ることがわかった。ただし、すべり速度が増えると摩擦係数が減少する特性と、断層面に作用するせん断応力が比較的大きい臨界状態にあることが条件となる。したがって、開発対象地域にある断層の摩擦特性と、周囲の応力状態を事前に把握することで有感地震の発生を予測し、さらに、その対策が可能と考えられる。

  3. ティップスクリーンアウトの可視化による現象解明とフラクチャリング制御の検討

    伊藤 高敏, 山本 晃司

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Challenging Exploratory Research

    研究機関:Tohoku University

    2016年4月1日 ~ 2018年3月31日

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    石油天然ガス生産に不可欠なフラクチャリング技術で問題となっているスクリーンアウト現象を室内実験で再現し,そのときのフラクチャー挙動をCTスキャナにより可視化することに成功した.そこで,軟らかい材料を用いることで小さい試験片でも可視化できる大きさにフラクチャーが開口するようにし,X線透過性に優れたCFRPと樹脂材料をうまく組み合わせた圧力容器を用いることで任意の軸対象三軸圧縮応力を負荷できるようにした.また,硫酸バリウムを添加した流体が流れと閉塞状況の観察に有効であることがわかった.

  4. 水圧破砕とコア変形原理を統合した自己補償型深部地殻応力測定法の構築と実用化

    伊藤 高敏, 清水 浩之, 林 為人, 船戸 明雄, 名雪 利典, 加藤 和政

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (A)

    研究機関:Tohoku University

    2012年4月1日 ~ 2015年3月31日

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    本研究では、多方面で関心が高まっている、深度数kmにおける地殻応力の原位置測定を可能とする実用的な方法を提案して実証した。これによれば、水圧ポンプを組み込んだ坑内ツールを用い、坑底に設けた補助孔(ベビー孔)で水圧破砕を行うことでコンプライアンスが十分小さい加圧系を実現し、ワイヤーライン式ツールにつきまとう抑留リスクを、ドリルパイプの中でツールを昇降させることで回避し、検出が極めて困難な水圧破砕き裂の方位を用いず、ベビー孔のコアの形状を解析して地殻応力の方位を決定し、同時に得られる地殻応力差を使って水圧破砕法で得た結果を補償し、さらに、水圧破砕法が原理的に内包する測定範囲の限界を排除できる。

  5. 孔内実験・計測による地震準備過程の状態・物性の現場把握

    木下 正高, 伊藤 久男, 林 為人, 伊藤 高敏, 加納 靖之, 荒木 英一郎, 山岡 耕春

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research on Innovative Areas (Research in a proposed research area)

    研究機関:Japan Agency for Marine-Earth Science and Technology

    2009年7月23日 ~ 2014年3月31日

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    地震発生断層上での応力場・力学・水理特性等の把握のため、孔内検層・実験・解析を行った。 南海掘削では、コア法(弾性・非弾性)、速度検層、水圧破砕実験、VSP、3D地震探査記録という、スケールの異なる様々な手法で推定された浅部応力場が互いに整合的で、水平最大圧縮方向がプレート運動方向に一致した。また、孔内長期観測所の温度データから、分岐断層(~5000m)の温度が130-150℃と推定された。 東北掘削では、地震時に浅部で応力降下が起こったこと、また、プレート境界周辺での温度異常が予測より少ないことから定常摩擦係数が0.1以下と極めて小さいことが判明し、3.11地震時の大規模すべりを支持した。

  6. CO2地中貯留のためのCO2反応性グラウトによる人工バリアー形成法の構築

    伊藤 高敏, 関根 孝太郎, 佐藤 晃, 當舎 利行

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    2009年 ~ 2011年

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    CO2地中貯留の上部を覆うキャップロックの欠陥を通して漏洩が起きた場合に、その漏洩を人工的に修復するための方法として原位置反応法を提案した。これは、漏洩箇所の近くにある観測井、あるいは新たに掘削した坑井を通じて注入した適当な溶液と漏洩したCO2が混合して生じる反応生成物によって漏洩箇所を充填するものである。そこで、同法の基本原理を室内実験で確認すると共に、フィールドに適用した際の挙動を数値シミュレーションで予測し、その有効性を検証した。

  7. メタンハイドレート開発のためのCO2ハイドレートを利用した浸透特性改質の研究

    伊藤 高敏

    2009年 ~ 2010年

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    日本近海の深海底面下にあるメタンハイドレート(MH)が天然ガス代替エネルギーとして期待されている.MH層にフラクチャーを導入できれば,刺激の負荷とメタンガスの生産を効率よく実施できるはずである.しかし,MH層ではフラクチャー表面からの逸水が大きく,フラクチャーを十分に大きくすることが容易ではないことが予想される.一方,MHが存在する温度・圧力環境ではCO2もハイドレート化を起こす.本研究では、この性質を利用してフラクチャー面からの逸水を抑制する可能性を検討した.昨年度には,噴霧ノズルを用いることで微粒状のCO2を分散させた水(CO2エマルション)を作成できること,また,そのエマルションを適当な温度・圧力環境に置くことでCO2ハイドレートが形成され,攪拌を行えば十分間程度の短い時間でハイドレートの形成が起こることを明らかにした.それを踏まえて本年度では,エマルションを多孔質体に圧入したときの挙動を調べる室内実験を行った.そこで,圧入に必要な量のエマルションを作成するための装置,ならびに,そのエマルションを円柱状多孔質体に開けた坑井に圧入するための装置を作製した.実験の結果,水を流しただけでは何も変化が起きなかったのに対して,エマルションを流した場合には,攪拌や保持時間を要すことなく,流量一定の条件でも注入圧が徐々に大きくなっていくことがわかった.この現象は,発生したCO2ハイドレートが多孔質体の間隙を埋め,浸透率を低下させたことで起きたものと考えられる.これらのことから,CO2ハイドレートによってフラクチャー面からの逸水を抑制できる可能性が明らかとなった.

  8. 地域の再生可能エネルギシステム設計法の構築:岩瀬湯本地区における実践的アプローチ

    新妻 弘明, 浅沼 宏, 森谷 祐一, 伊藤 高敏, 村岡 洋文, 相馬 宣和

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (A)

    研究機関:Tohoku University

    2006年 ~ 2008年

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    福島県天栄村湯本地区で既存の坑井(1600m)を水圧刺激し, AEの超解像マッピング解析や坑井試験の結果をもとに, 地下構造・地下性状の情報取得を行った。さらにEIMYの概念に基づき, 熱エネルギー, 地下水資源,経済性の点で持続可能なシステムの設計法を検討し, 地域のためのエネルギーシステムを設計した。また, 同地域で地中熱ヒートポンプの実証試験を行い, 条件有利地域での特性を明らかにした。

  9. CO2地中固定のための人工バリアー

    伊藤 高敏, 関根 孝太郎

    2006年 ~ 2007年

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    地球温暖化抑制のため、火力発電所等の排ガスから分離・回収したCO2を,地下深度1km前後にあって,間隙率の比較的大きな岩石からなる地下帯水層に圧入して溶解・固定化するという方法が検討されている.また,この方法では,浸透性が小さい天然の構造性バリアー,すなわちキャップロックが存在することを前提とし,その下部にCO2を圧入することになっている.しかし,地殻活動が盛んな日本では,そのように健全で広大なキャップロックがある場所は限られている.そこで本研究では,現位置反応法で形成した人工バリアーによってキャップロックの欠損部を覆い,また,断層等の移動経路を遮断してCO2の漏洩を防止するという,従来にない新技術を開発する.この目的を達成するために本年度は,以下のことを実施した.まず昨年度の実験結果を再検討した結果,模擬岩石の浸透率を計測する際の差圧の測定方法に問題があって計測値に大きな誤差を含む可能性のあることが判明した.そこで,高圧環境下で作動する高精度の差圧計を導入し,さらに,模擬岩石内部の流れが均一になるような工夫を新たに加えることで,その問題点を解決した.また,CO2と反応する溶液(反応性グラウト)の新たな候補として水ガラス溶液を用いて実験を行った結果,昨年度に用いたCa (OH)2水溶液よりも粘性が十分小さい上に現位置反応による浸透性低下量も大きく,実用に十分適するものと判断された.

  10. 最大応力計測問題を打開する水圧破砕法国際スタンダードの構築と検証

    伊藤 高敏, 関根 孝太郎, 伊藤 久男, 小村 健太朗

    2006年 ~ 2007年

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    水圧破砕法は,km級の大深度における地殻応力の現位置計測を可能とする唯一の実用的手段として従来から広く用いられてきた.しかし,この方法では,坑井直交面内における最大応力を評価する要領に致命的な欠陥のあることが最近明らかになっている.その原因は,従来の仮定に反し,(a)残留き裂開口幅の存在によって,き裂の開口以前から坑井水圧がき裂内に浸入してしまうこと,(b)加圧システムのコンプライアンスC(システム内の水圧を単位量だけ増加させるのに必要な水の体積,換言すると剛性の逆数)が大きすぎるために,き裂開口の影響が坑井水圧の変化挙動に現れにくいことにある.これらを考慮して大深度での計測を可能にすべく我々は,坑井底部に直径の小さい試験孔(以下,ベビー孔)を新たに掘削して,その中で水圧破砕を実施するという新方式(Baby Borehole Hydro-fracturing, BABHY(ベイビー方式と呼ぶ))を提案した.その実用化を図るために本年度には,当初計画の通りにポンプユニットの製作に成功し,そして,それを組み込んだ,深度1キロまでの測定に耐える地殻応力測定装置の開発に成功した.さらに、地表から掘削された鉛直井に同装置を適用して,深度811mでの実証試験に成功した.また,同フィールド試験で用いたパッカー装置と大型試験片(700×700×1000mm3)による室内水圧破砕実験を実施した,圧力データと模擬地殻応力の関係が,我々の提案する理論(1/2理論と命名)通りであることを再検証した.

  11. 最大応力計測問題を打開する水圧破砕法国際スタンダードの構築と検証

    伊藤 高敏, 関根 孝太郎, 伊藤 久男, 小村 健太朗

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    2006年 ~ 2007年

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    水圧破砕法は,km級の大深度における地殻応力の現位置計測を可能とする唯一の実用的手段として従来から広く用いられてきた.しかし,この方法では,坑井直交面内における最大応力を評価する要領に致命的な欠陥のあることが最近明らかになっている.その原因は,従来の仮定に反し,(a)残留き裂開口幅の存在によって,き裂の開口以前から坑井水圧がき裂内に浸入してしまうこと,(b)加圧システムのコンプライアンスC(システム内の水圧を単位量だけ増加させるのに必要な水の体積,換言すると剛性の逆数)が大きすぎるために,き裂開口の影響が坑井水圧の変化挙動に現れにくいことにある.これらを考慮して大深度での計測を可能にすべく我々は,坑井底部に直径の小さい試験孔(以下,ベビー孔)を新たに掘削して,その中で水圧破砕を実施するという新方式(Baby Borehole Hydro-fracturing, BABHY(ベイビー方式と呼ぶ)を提案した.すなわち,(a)先端にコアビットを取り付けた部品を掘管内部を通して坑底まで自由落下させて掘管内壁に固定,(b)同ビットを使って本体坑井底部にベビー孔を掘削,そして,(c)ビットを回収した後,今度はストラドルパッカーを同じく掘管内部を通して坑底までワイヤーラインで降ろし,掘管内壁に固定,ベビー孔内で水圧破砕を実施し,その結果から地殻応力を評価するというものである.その実用化を図るために室内実験と岐阜県松代町における深度約80mの坑井を用いた現場試験を行って要素技術の開発を行った.その結果を踏まえて深度1キロまでの測定に耐える地殻応力測定装置を試作した.さらに,地表から掘削された鉛直井に同装置を適用して,深度811mでの実証試験に成功した.

  12. マグマ内揮発性物質による火道内部の増圧過程の解明

    西村 太志, 吉田 武義, 中村 美千彦, 伊藤 高敏, 中嶋 悟, 寅丸 敦志

    2002年 ~ 2006年

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    本研究は,火山爆発の発生前のマグマの状態と爆発的噴火プロセスの関係を明らかにすることを目的とし,これら爆発的噴火の準備に関する一連のプロセスを,発泡過程,脱ガス過程,火道開口・閉塞過程などの素過程に分解し,主に,実験的,理論的な研究を進めた.また,これらの過程を統合したモデルの構築や,噴出物の複数解析や他現象との比較検討に基づき,火道内の増圧過程やマグマプロセスを調べた.脱ガス過程について,主に室内実験の結果から以下のことが明らかとなった.マグマ内に剪断破壊により生じた通路や気泡連結による通路が生じている場合,浸透脱ガス流とともに気泡吸収がマグマ内で生じ,マグマ内に気泡の無い層を形成する可能性がある.また,発泡が十分進んでいない深い領域でも,剪断応力が大きい火道壁近傍などでは気泡が十分連結するため,脱ガスが進行することがある.火道や亀裂の閉塞過程の実験によって,高温マグマの貫入時には熱により周辺岩体が大きく変形し通路を閉塞することがあること,火山下の熱水流動による火山ガラスの水和・変質・溶脱過程により火山体を構成する媒質の浸透率が3桁以上変化すること,が明らかとなった.また,カルデラ崩壊とプルトン貫入の関係をもとに,カルデラの火道形成過程を考察した.マグマ上昇モデルの数値計算から,爆発的噴火前には,マグマが浅部に近づくにつれ揮発性物質の発泡によるマグマの体積増のため地殻変動が急速に進行するのに対し,非爆発的噴火の前には,脱ガスによるマグマ体積の減少が起こるため,急速な地殻変動は観測されないことが明らかとなった.火山噴出物解析を行い,火山灰の火山ガラスの特徴と,地震観測等の力学的条件から区別される桜島の爆発的噴火様式の関係を調べた.また,火山噴出物の水の実効的な拡散係数,色変化特性,浸透率測定から,発泡のその場観測などからマグマ上昇過程に関連した時間スケールを議論した.

  13. 冷却に伴うき裂透水性の変化挙動を支配する臨界温度差の存在

    伊藤 高敏

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (C)

    研究機関:Tohoku University

    2003年 ~ 2004年

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    岩体中のき裂に沿って低温の流体が流れれば,岩体の温度は初期状態よりも大なり小なり低下する。さらに,温度が低下すると岩体の熱収縮が起こり,この結果,き裂が開口してその透水性が増大すると一般には考えられている。しかし,岩体が大きな地殻応力の作用する圧縮応力場にあることを考えると,熱収縮によってき裂が開口しようとしても,大きな地殻応力がそれを妨げてしまう可能性もあり,き裂の透水性が冷却と共に単純に増大するかどうか定かではない。そこで本研究ではまず,地下岩体の一部が円柱状ないし球状に冷却されるというモデルにより,冷却部に生じる応力低下量を見積もる解析解を誘導した。さらに,その岩体が遠方に作用する応力(地殻応力)で圧縮されている場合に,冷却に伴う熱応力の発生によって冷却部の応力が丁度零になる条件を調べたところ,地殻応力と岩体物性で一意に決まる臨界値まで温度を下げれば良いことがわかった。この検証を目的として,以下のような室内実験を実施した。まず,岩石からなる中空円筒とその内側に丁度収まる大きさの円柱を用意し,その円柱部を円筒部の内側に差し込んだ状態で両端を切断したものを試験片とする。ここで,円筒部と円柱部の間の隙間がき裂となる。次に試験片を軸対称三軸圧縮試験機に取り付け,封圧と試験片外周温度を適当な値に設定する。そして,き裂に低温の水を流して試験片の中心部を冷却し,それに伴うき裂透水性の変化を注水の流量あるいは圧力から評価する。実験の結果,注水温度に対して試験片外周温度を上昇させると,ないしは試験片外周温度に対して注水温度を相対的に低下させると,両者の温度差がある大きさを超えたときにき裂の透水性が急増するという現象が現れた。また,この結果は有限要素法による数値シミュレーションによる予測と良く一致した。

  14. ボーリングに伴う坑井壁面き裂(DTF)の発生機構とその制御法に関する研究

    伊藤 高敏, 山本 晃司, 林 一夫

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (C)

    研究機関:Tohoku University

    2001年 ~ 2002年

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    DTF(Drilling Induced Tensile Wall Fracture)は坑井壁面にしばしば観測される、軸方向にエシェロン状に並ぶき裂状構造である。その名の示す通り、引張破壊によってそのような構造が形成されると考えられているが、単に岩体の層構造が際だって見えているだけという批判もあって詳細は不明である。しかし、DTFが本当に引張で形成されたものだとすると、場合によってはDTFが合体(リンク)、拡大成長して大量逸泥に至る可能性がある。一方、DTFの向きや深度の情報から地殻応力を評価できることが示されており、それらの事項を考える上での前提となるDTF形成機構の解明が望まれている。そこで本研究では、まず理論解析を行い、円孔の応力集中と泥水と岩体間の温度差ΔTによる熱応力によってDTFが発生し、き裂干渉によってDTFがリンク、成長するというモデルと各プロセスに至るために必要な条件を明らかにした。その結果、地殻応力状態に応じて坑井の向きを変えることでDTFの発生と成長を抑制できる可能性が明らかになった。そこで、室内実験を実施してDTFを実際に造り、理論モデルとの比較検討を行った。ただし、実験ではDTF発生挙動を直接観察できるように模擬岩体として200mm角のアクリル樹脂ブロックを用い、直径20mmの模擬坑井に約-200℃の液体窒素注入することで温度差ΔTを加えた。この結果、フィールドで実際に観測されているDTFのように坑井軸から傾斜し、ほぼ等間隔に並ぶき裂群が形成され、条件によってはき裂同士が互いにリンクするように成長することがわかった。また、そのき裂形成とリンク挙動は上述のモデルにほぼ従うことがわかった。

  15. 微小き裂閉口に伴う岩体の電気特性変化を利用した地殻応力モニタリング

    伊藤 高敏, 斉藤 玄敏, 林 一夫

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (C)

    研究機関:Tohoku University

    1999年 ~ 2000年

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    本研究では,従来法の欠点を克服し得る新しい概念に基づく地殼応力計測法の可能性を理論的,実験的に検討することを目的とする.同法では,岩体に外力を負荷すると岩体のマクロな電気伝導度が変化するという現象を利用する.このため,まず,岩石比抵抗(電気伝導度の逆数)の基本特性を室内実験によって調ベた.その結果を踏まえて,次に,地殼応力場中にあるボアホール周りに発生する比抵抗分布を,ボアホール壁面に設置した電極を用いて測定する可能性と,その結果から地殻応力を評価する可能性を主に理論解析を行って検討した.この結果,ボアホール壁面の周方向に,等間隔で配置した4つの電極を用い,いわゆる四極法によってボアホール壁面における見掛け抵抗を測り,その結果から,ボアホール周りの比抵抗を評価する場合,電極間隔を5゜程度にすれば,ボアホール壁面の極近傍,すなわち,ボアホール壁面からボアホー 半径の1割程度の範囲の比抵抗を測定できることがわかった.また,四極法の測定結果から以下のようにして地殻応力を評価できることがわかった.まず,周方向に加え,ボアホール軸方向にも周方向と同じ間隔で電極を配置し,ボアホール壁面の見掛け抵抗を測定する.このようにして測定した周方向と軸方向の見掛け抵抗の差は,測定位置のボアホール壁面が受けている周方向応力と軸方向応力の差に正比例する.両者の比例定数は,測定対象深度のコアが有れば上記の室内実験によって決定でき,また,ボアホール壁面における周方向応力と軸方向応力の差は,地殻応力の関数として与えられる.これらのことから,周方向と軸方向の見掛け抵抗の差が最小になる方向として,水平面内の最大主応力の方向が求められる.さらに,鉛直方向の地殼応力を被り圧(静岩圧)で既知とすれば,周方向角度の異なる2カ所の見掛け抵抗測定結果から,水平面内における最大及び最小の地殻応力の大きさを評価できる.

  16. キャビテーション噴流式表面改質装置の試作

    祖山 均, 浦西 和夫, 渡辺 豊, 伊藤 高敏

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B).

    研究機関:Tohoku University

    1998年 ~ 2000年

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    1.キャビテーション噴流用ノズルを0.4mmから1.9mmまで大口径化したキャビテーション噴流式表面改質装置を試作した。 2.試作した上記装置を用いて,PVDFセンサによりキャビテーション衝撃力を測定し,ノズル口径を約5倍にすると,衝撃力の発生頻度が増大するばかりでなく,最大衝撃力も5倍以上増大することが判明した。また試料水中の溶存酸素量と衝撃力の関係を計測した結果,溶存酸素量を減らすと衝撃力が増大することを明らかにした。 3.試作した装置で種々の加工速度で表面改質した試験片の硬さと残留応力などを計測して最適加工速度を明らかにした。また硬い材料ほど圧縮残留応力を導入しやすいことを明らかにした。耐食性向上における最適加工時間については,キャビテーション噴流を噴射した時間と噴射後の材料表面の腐食電位の関係から,炭素鋼S45Cの耐食性の向上における最適加工速度を明らかにした。 4.キャビテーション噴流を噴射中の被加工面の電位と作動流体のpHの関係から,プルベイ線図より,キャビテーション噴流式表面改質装置の最適作動流体を明らかにした。 5.歯車や歯車を模したV溝付試験片の表面改質を行い,ショットピーニングに比べて,被加工面の粗さを増大することなく表面改質が可能であることを明らかにした。また金型等に用いられる硬い材料SKD61にもキャビテーション噴流により圧縮残留応力を導入できることを実証した。 6.回転曲げ疲労試験により,試作した上記装置で表面改質した試験片の疲労強度が未処理の試験片に比べて増大し,本表面改質法により高強度化を行えることを実証した。また電気化学的計測により,本表面改質法により炭素鋼の耐食性を30%程度向上できる明らかにした。

  17. ブレイクアウト発生機構の解明と大深度地殻応力評価への応用に関する研究

    林 一夫, SONG Insun, 齋藤 玄敏, 伊藤 高敏, HAIMSON Beza, BEZALEL Haim

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for international Scientific Research

    研究機関:Tohoku University

    1997年 ~ 1998年

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    本研究は、ボアホールブレイクアウトの発生機構と成長プロセスを明らかにして、大深度での地殻応力評価法の確立に資することを目的とする。まず、坑井周りに発生する応力場を、弾塑性有限要素解析により明らかにし、特に、坑底近傍に着目して、応力場の特性を抽出して、ボアホールブレイクアウトの発生機構を検討した。次に、この応力場を基にして、坑井の掘進長の増大に伴う応力場の変遷を近似的に表現する擬似2次元応力場モデルを構築し、ブレイクアウト成長プロセスを明らかにした。破壊基準としてはモール・クーロンの破壊基準を用いた。得られた結果を要約すると以下の通りである。 1. 坑底近傍には、坑底から離れた領域とは異なる方向に大きな相当応力が発生するがその大きな相当応力が発生する領域の大きさは坑井半径に比べて非常に小さい。すなわち、坑底の特異な応力場は、3次元的に非常に局所的である。 2. 破壊特性が、局所的な応力状態に鈍感な岩体においては、坑底近傍では破壊は起きず、坑底から離れた位置で破壊が起きる。このため、ブレイクアウトの発生方位は坑底から離れた位置で決まることになる。 3. 応力場の変遷は、原理的には、負荷経路に依存するが、結果的には、坑底の影響がほとんど全く現れてこない。この特性は、遠方応力場を種々変化させても保存されている。 4. 従って、現場で観測されるブレイクアウトは、上述の負荷履歴依存性には無関係に、円柱状空堝を有する無限体の応力場と同一の応力場の下で形成されたと考えて良い。 5. ブレイクアウトの幅は、弾性解析で求まる応力場から推定される幅とほとんど同一である。これは、Haimson等によって提唱されているブレイクアウト幅と地殻応力との関係に関する仮説が定量的に正しいことを示している。

  18. 坑井掘削により生じるき裂を用いた大深度地殻応力計測評価法の開発

    林 一夫, 岡部 高志, 伊藤 高敏

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for Scientific Research (B)

    研究機関:Tohoku University

    1996年 ~ 1998年

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    本研究は、地下数キロメートル以深の岩体の現位置応力の計測を可能ならしめる新しい方法を開発する事を目的としたものである。具体的にはドリリングインデューストフラクチャー(DTF)が保持する応力場に関する情報を利用して応力場を推定する。DTFは坑井周方向の発生位置及び斜め微小き裂の坑井軸方向となす角度によって特徴づけられる。従って、基本的には、坑井の各深度でDTFのデータから、応力場に関する2つの情報を得ることができる。単独の傾斜井で各種検層により3深度以上の深度でDTFが計測されれば、6個の未知応力成分に対し、互いに独立な6個以上の観測方程式を得ることができる。このことを利用し、DTFデータに基づく応力場評価のための逆問題を構築するとともに、その標準的解析法を新たに開発し、パーソナルコンピュータレベルで解析可能なプログラムコードを開発した。DTFデータの読みとり誤差に鑑み、逆問題解析には正規乱数を利用した統計的手法を導入した。DTFデータのみならずボアホールブレイクアウト(BO)に関するデータも併用可能である。種々の応力場を想定した数値実験を行い、本逆問題解析法の妥当性を確認し、さらに、3本の地熱井、すなわち、湯の森のTG-2井、肘折のHDR-2井及び英国HDRテストサイトのRH-15井で採取されたデータを用いて逆問題解析を実施して応力場を推定し、本研究で開発した手法の、フィールドへの適用性並びに有効性を確認した。なお、地熱井を対象とする場合には熱応力の影響について検討が必要である。この点についても検証を行い、TG-2井では、約1000m程度の深度において熱応力が10MPa以下であればこれを無視しても評価結果に大きな影響を生じないことも明らかにした。

  19. 微小き裂閉口に伴う岩体の電気特性変化を利用した地殻応力モニタリング

    伊藤 高敏

    1997年 ~ 1997年

  20. 地下き裂開口挙動直接計測による地殻応力の高精度評価に関する基礎研究

    伊藤 高敏

    1996年 ~ 1996年

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    本研究では,パッカーを膨張させて縦き裂のあるボアホール壁面に押しつけることで壁面に圧力を負荷した際の壁面の周方向変位から,岩体の地殻応力(初期応力)を計測評価する新たな方法を検討した.このため,バッカー外周にとりつける周方向変位測定素子を試作した.試行錯誤の結果,同素子としては,ひずみゲージを絶縁性の材料で挟み込んだ構造で,また,パッカーが膨張して坑井壁面に押しつけられるまでに発生するひずみを極力除去するために,接着せず,浮かせてパッカー表面に取り付ける構造とするのがよいことがわかった.この測定素子を,本研究で新たに作成した室内実験用の小型パッカーに取り付け,その特性を模擬坑井を使って調べた.模擬坑井はアルミ製および天然の安山岩製の二種類で,坑井中心を通る対称面が分離できる構造をしており,その分離面をき裂面と見なし,地殻応力を模擬するために試験片側面に加えた圧縮応力と上記で測定したボアホール壁面の周方向ひずみの関係を調べた.この結果,上記測定法によれば,ボアホール壁面の周方向ひずみとパッカー膨張圧の関係が,昨年度の数値シミュレーションで明らかにしたようにき裂開口圧付近で大きく変化する現象を明確に捕らえられることがわかった.これにより,上記測定法によっていわゆるき裂開口圧を精度良く評価できることがわかった.また,測定された周方向ひずみとパッカー膨張圧の関係より,岩体の縦弾性係数とポアソン比を計測する方法を提案した.この方法を上記の実験結果に適用して弾性定数を求め,他の実験結果と比較した結果,両者が非常に良く一致していることがわかった.

  21. 電気容量型変位計の原理による地下き裂開口挙動評価のための基礎研究

    伊藤 高敏

    1995年 ~ 1995年

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    本研究では,パッカーを膨張させて縦き裂のあるボアホール壁面に押しつけることで壁面に圧力を負荷した際の壁面の周方向変位から,岩体の地殻応力(初期応力)を計測評価する新たな方法を検討した.このため,有限要素法によって壁面圧力によるボアホール変形挙動を解析した.また,ボアホール壁面の周方向変位を測定する具体的方法について実験的に検討した.得られた知見をまとめると次のようになる.(1)ボアホール壁面圧力S_Pが零の状態からの壁面上における周方向ひずみの増分Δε_θは,初めのうちはS_Pに対して線形に増加するが,き裂開口開始から両関係のこう配が変化する.(2)この傾向は,ボアホールに直交する平面内に作用する地殻応力の比S_1/S_2を1から3の範囲で種々変化させた結果についても同様であった.(3)よって,何らかの方法でΔε_θを測定できれば,測定して得られたΔε_θ vs S_P曲線のこう配の変化からき裂の開口開始を検出でき,き裂開口開始時のS_Pの大きさとしてき裂開口圧P_rの大きさを評価できる.さらに,その結果をき裂閉口圧等の通常の水圧破砕計測結果を組み合わせればS_1およびS_2それぞれの大きさを決定できる.(4)上記方法具体化のため,加圧中のボアホール壁面上の周方向ひずみを測定する装置を試作し,その性能をボアホールを鋼管で模擬した室内実験で評価した.この結果,当初予定していた電気容量型変位計の原理では測定が困難であることがわかった.そこで,ひずみゲージを基本とする素子を作成し,それを用いれば加圧中に周方向ひずみを測定できることを明らかにした.

  22. マグマ熱抽出のためのマグマ内熱交換システムの力学的安定性に関する固体力学的研究

    林 一夫, 伊藤 高敏

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for General Scientific Research (C)

    研究機関:Tohoku University

    1994年 ~ 1995年

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    本研究は、マグマからの直接熱抽出に於けるマグマ内熱交換システム(固化マグマ)の力学的安定性に関する検討を行ったものである。まず、固化マグマの材料力学的基本特性である構成則について検討を行った。すなわち、一軸状態のクリープひずみの応力依存性についてはNorton則を用い、応力のべき乗に比例するとした。クリープひずみの時間依存性については、第二期クリープを想定して、線形関係を置き、また、温度依存性については、Arrhenius則を採用した。さらに、多軸応力下に対しては、クリープポテンシャルとして、偏差応力の第二不変量を用いた流れ則を適用し、これに前述の一軸応力-ひずみ関係を与えて、三種の岩体すなわち、花崗岩、斜長岩及びカンラン岩の構成関係式を構築した。温度環境としては、次の二つの状態を代表的なものとして取り上げた。すなわち、マグマの対流が極めてゆっくりとしていて、固化域の大きさがマグマの固相線温度により決まってしまう場合と、マグマの対流が活発で固化域の大きさが主として熱バランスで決まってしまう場合の二通りの場合である。この二通りの場合について、まず熱交換システム内の、熱移動解析を実施し、固化域内の温度分布の経時変化、固化域の成長・退縮挙動を明らかにした。さらに、上記の構成関係式を用いて応力場を解析し、その特徴を明らかにするとともに、坑井近傍の破砕帯形成の観点から、各岩種の、マグマエネルギー直接抽出への適応性について評価した。その結果、上述の二通りのいずれの場合も、花崗岩、斜長岩及びカンラン岩の三者の内カンラン岩が、坑井近傍に破砕帯を最も形成しやすい性質を有し、従って熱抽出に最も適しており、斜長岩がこれに次ぐことがわかった。花崗岩が最も不向きである。

  23. 地下き裂の力学特性を応用した地殻応力計測評価のための真のき裂開口圧計測法の開発

    伊藤 高敏

    1994年 ~ 1994年

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    本研究では,水圧破砕で作成したき裂が再加圧によって開き始めるときのボアホール水圧(真のき裂開口圧)から地殻応力を評価することを目的として,一定圧入流量で再加圧した際のボアホール水圧一時間曲線が線形から非線形になるときのボアホール水圧(見かけのき裂開口圧)の情報から真のき裂開口圧を評価する方法を明らかにし,これを実フィールド実験によって検証した.得られた知見をまとめると次のようになる.(1)真のき裂開口圧と見かけのき裂開口圧の間に差が生じる主な原因は,き裂が開口したことによって増加する加圧体積の水圧に対する増加率(以下,き裂体積増加率と呼ぶ)の大きさにある.つまり,き裂が開口した直後では,き裂体積増加率があまり大きくないために,二つのき裂開口圧の間に差が生じてしまう.(2)ただし,有効加圧系体積と呼ぶ加圧系内の水の体積に相当する量を小さくすることによって,再加圧時のボアホール水圧一時間曲線に及ぼすき裂体積増加率の影響を大きくすることが可能である.この結果,有効加圧系体積が小さいほど,見かけのき裂開口圧は真のき裂開口圧に近づいて行く.(3)したがって,有効加圧系体積を十分小さい水圧破砕システムを用いれば,そのとき測定された見かけのき裂開口圧から真のき裂開口圧を近似的に評価することができる.さらに,き裂面垂直方向の地殻圧縮応力の大きさがき裂閉口圧を利用するなどして既知であるものとすると,その結果と真のき裂開口圧の測定結果からき裂線方向の地殻圧縮応力の大きさを評価できる.(5)なお,有効加圧系体積の大きさは,単純に図面上の幾何学的形状か評価される加圧系内の水の体積とは必ずしも一致せず,加圧系全体のコンプライアンスを考慮して評価しなければならない.

  24. 注水停止後の逸水に伴う地下き裂閉口特性を応用した地殻応力計測評価に関する研究

    伊藤 高敏

    1993年 ~ 1993年

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    本研究では、ボアホールと直交する横き裂が存在する場合を対象として、シャットイン後のき裂閉口挙動を解析し、シャットイン後のボアホール水圧降下曲線(シャットイン曲線)とき裂閉口挙動との関係を解明して、き裂閉口圧決定法を提案するとともに室内実験による検証を行った。この結果得られた知見をまとめると次のようになる。(1)ボアホールと直交し、かつ、ボアホール軸に対して軸対称な地殻圧縮応力を受ける横き裂を対象とし、シャットイン後のき裂閉口挙動を解析してシャットイン曲線を求め、それに及ぼす諸因子の影響について検討した。その結果、次のことがわかった。すなわち、ボアホール水圧の大きさがき裂面垂直方向の地殻圧縮応力の大きさに等しくなったとき、き裂全体が同時に閉じてしまう。また、シャットイン曲線の形状はき裂長さが変わってもほとんど変化しないが、逸水係数の影響は強く、逸水係数が大きくなるほどシャットイン曲線のこう配が大きくなる。また、逸水係数が同じでも、き裂閉口挙動の違いから、縦き裂の場合の方が横き裂の場合よりシャットイン曲線のこう配が全体的に大きくなる。(2)横き裂のシャットイン後の水圧降下には、シャットイン直後に起こるき裂進展が終了してからき裂が閉じるまでの段階およびき裂全体が閉じた以降の段階の各段階で、ボアホール水圧の時間変化率の逆数がボアホール水圧に比例するという特性がある。(3)上記の特性を利用すれば、き裂閉口圧を明確に決定できる。すなわち、シャットイン曲線をボアホール水圧の時間変化率の逆数とボアホール水圧との関係に整理し直し、それを二直線近似したときの二直線の好転を検出すれば、その交点のボアホール水圧として、き裂閉口圧が与えられる。

  25. 流体圧による地下き裂開口挙動特性を応用した地殼応力計測評価法に関する研究

    伊藤 高敏

    1992年 ~ 1992年

  26. 地下岩体の現位置通水特性の高精度計測評価法に関する研究

    林 一夫, 伊藤 高敏

    1992年 ~ 1992年

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    平成2年度では,従来圧力パルス試験のネックとなっていた圧送水の遷流の問題及び加圧系コンプライアンスの問題の2つの問題を解決した。平成3年度では,微細き裂の選択方位により生じる異方性の問題を解決した。計画の最終段階に当たる平成4年度では,圧力依存性の検討を行うことのできる方法を開発した。この方法は,基本的には,加圧区間水圧を一定に保ったときの,還流流量の応答を見るものである。まず,試験坑井の加圧区間に所要の一定圧力を負荷し保持したときの熱交換層内の流れを解析し,このときにパッカーエレメントを越えて試験坑井内に還流してくる水量の経時変化と通水特性との相関を定量的に明らかにした。次に,この相関を基準にして,フィールド計測データから,現位置通水特性を評価するための方法を開発した。具体的には,以下の手順で行う。ストラドルパッカーシステムを,ボアホールの所定深度にセットし,加圧区間を所要の設定圧に一定に保って加圧し,ボアホール内への還流流量の経時変化を計測する。これを保数時間軸に対しプロットし,時間が十分経過した部分で得られる直線部の傾きと,この直線部を還流流量が零となる所へ外挿したときの時刻を求める。設定圧に対する通水特性は,この傾きと時刻から,本研究で得た算定式を用いて求めることができる。この手順による現位置計測及び評価を,加圧区間水圧の設定値を種々変化させて実施することにより,通水特性の貯留層圧依存性を把握することができる。前述の算定式には,ストラドルパッカーシステムの加圧区間長さ,パッカーエレメント長さ及びボアホール半径の諸寸法によって決まる係数が入っているが,本研究では,この係数の寸法依存性に関するデータも明らかにしており,従って,本方法はパッカーシステムの寸法によらず用いることができる。また,本方法では,加圧系内の水圧の経時変化はないので,コンプライアンスの影響を受けない。

  27. 地殼応力の三次元計測評価における圧力データの物理的背景に関する破壊力学的研究

    林 一夫, Z. ZHAO, M.Y. LEE, 伊藤 高敏, B.C. HAIMSON, ZHAO Z., LEE M.Y., HAIMSON B.C.

    提供機関:Japan Society for the Promotion of Science

    制度名:Grants-in-Aid for Scientific Research

    研究種目:Grant-in-Aid for international Scientific Research

    研究機関:Tohoku University

    1991年 ~ 1992年

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    水圧破砕による地殼応力計測法は,深部の地殼応力を定量的に計測できるほとんど唯一の方法として,世界各国で実施例が積み重ねられて来たが,この経験を通して,従来の水圧破砕地殼応力計測法には多くの問題点が内在していることが,しだいに明らかになって来た。この基本的な原因は,水圧破砕地殼応力計測法において用いられる基礎観測データすなわち破断水圧,き裂開口圧及びき裂閉口圧の物理的意味が未解明のまま実用に供されて来た点にある。本研究は,岩石破壊力学に基づくアプローチと室内模擬水圧破砕実験とにより,上述の物理的意味を検討するとともに,観測データの客観的決定法を開発したものである。 継続2年計画の初年度である平成3年度では,破断水圧及び縦き裂の閉口圧についての検討を行った。破断水圧については,水圧破砕時の坑井壁からのき裂初生に関する局所応力破壊基準なる新しい基準を導入することで,破断水圧に加圧速度依存性及び坑井半径依存性を明解に説明することに成功した。さらに,室内模擬実験による検証を行った。従来,破断水圧は上述の2つの依存性の物理的背景が未解明であったため,データとしては重要視されていなかったが,本研究により,き裂面垂直方向の応力のみでなくこれと直交する2方向の応力の情報も含んだ極めて重要なデータとして使用できることが明らかになった。縦き裂のき裂閉口圧については,まず,破壊力学に基づく数値シミュレーションを実施して,水圧破砕により作成されたき裂の,シャットイン後の閉口挙動を明らかにした。その結果,岩体内への水の透水によるき裂内水圧の減少により引き起こされるシャットイン後のき裂閉口過程は,次の3つの段階に分けることが出来ることがわかった。すなわち,き裂全体が開口している状態から開口変位が漸減しき裂先端が閉じ始めるまでの第1段階,き裂閉口部が坑井表面に向かって広がりき裂全体が閉じるまでの第2段階,これ以後の第3段階である。しかも,最小地殼圧縮応力は第1段階の終端部の水圧に極めて近いことがわかった。さらに,各段階において,水圧減少速度の逆数と水圧との間に線形関係が成立することを示し,このことを利用して,き裂閉口圧を確定的かつ客観的に決定する方法を開発した。次に,日米両者で実施した室内並びにフィールド実験で得られたシャットイン曲線を,水圧減少速度の逆数と水圧との関係で整理し,上述の知見,すなわち,3直線近似が成立することを実証すると供に,高圧側からみて第1,第2直線の交点から最小地殼圧縮力を決定出来ることを検証した。 平成4年度においては,破断水圧以降のき裂成長時のボアホール水圧挙動,き裂開口圧及び横き裂閉口圧の検討を行った。まず,き裂初生以降一定流量で加圧を続けた際のボアホール水圧の大きさと,き裂面垂直方向の地殼圧縮応力の大きさとの差は,き裂初生からの経過時間の立方根の逆数の正比例することを明らかにし,き裂面垂直方向の地殼圧縮応力の大きさを評価する方法を開発した。さらに,室内実験によりこの方法の妥当正を検証した。次に再加圧時のき裂開口挙動を数値シュミレーションで再現し室内実験で検証した。その結果,以下のことが明らかになった。すなわち,再加圧によりき裂が開口しても,すぐにはボアホール水圧と時間の関係に顕著な変化は現れず,ボアホール水圧と時間の関係が明らかに非線形になり始めるときのボアホール水圧(いわゆるき裂開口圧)は,き裂が実際に開口し始めるときのボアホール水圧より高くなる。しかも,このき裂開口圧は,き裂面内方向の垂直応力の影響をほとんど受けないとともに,圧入流量が小さくなるに従って,き裂面垂直方向の地殼圧縮応力の大きさに漸近してゆく。したがって,圧入流量を種々変化させてき裂開口圧を測定し圧力流入が小さくなるときの漸近似を求めることにより,その漸近値としてき裂面垂直方向の地殼圧縮応力を評価できることになる。最後に,横き裂の閉口挙動について解析を行った。その結果,閉口過程は,縦き裂の場合と同じく,き裂縁が閉じ始めるまでと,き裂全体が閉じるまで及びそれ以降の3段階に分けられ,第1,3段階では水圧の時間降下率の逆数と水圧の間に線形関係が存在し,き裂閉口圧は,第1段階終末での水圧として与えられることがわかった。

  28. マグマエネルギ-抽出のための地下システムの力学的安定性に関する固体力学的研究

    林 一夫, 伊藤 高敏

    1991年 ~ 1991年

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    マグマからの直接熱抽出における地下熱抽出システムの坑井周囲に形成される固化域の挙動を解明した。まず、固化域、部分凝固域および溶融マグマ内の温度場の熱抽出に伴う過渡的な応答の解析を行い、温度分布の経時変化を求めるとともに、固化域の成長、さらに熱抽出停止時の固化域の消滅過程を検討した。次に、得られた温度場を用いて、クリ-プを考慮した応力解析を花崗岩質、カンラン岩質および斜長岩質マグマに対して実施し、各岩質に対する固化域の応力分布の特徴およびその経時変化の特徴を明かにした。さらに、この応力解析をもとに、各岩質のマグマエネルギ-直接抽出システムに対する適用性について、開放型システムにおける坑井近傍の破砕帯形成の観点から評価した。得られた知見を要約すると以下の通りである。1.閉鎖型システムにおいては、熱抽出開始後短時間(400ー500時間)で固化域の成長がほとんどなくなる。これに対し開放型システムでは、はるかに長時間(1500時間以上)にわたって成長を続けその半径は坑井半径の30倍以上に達する。2.閉鎖型は、熱抽出停止後約1日で固化域が消失するのに対し、開放型では、消失までに約30日以上を要し、従って緊急停止後復旧までの猶予時間を十分長く見込める。3.坑壁での応力を調べた結果、花崗岩質クリ-プ特性を有する場合には、常に大きな圧縮応力が作用し周方向の割れは極めて生じにくい。これに対し、カンラン岩質クリ-プ特性を有する場合には、約5km以浅で、坑壁で周方向に引張応力が作用する。斜長岩石の場合には、この両者の中間の傾向がみられる。以上から、花崗岩質、カンラン岩質、斜長岩質の三者の内、カンラン岩質が熱抽出に伴って坑井周辺に破砕帯を最も形成しやすい性質を有し、開放型システムに適しており、斜長岩がこれに次ぐことになる。これに対し、花崗岩質の場合は、開放型熱抽出システムには不向きである。

  29. 流体を内部に含むき裂の力学特性を応用した地殼応力計測法を確立するための基礎研究

    伊藤 高敏

    1991年 ~ 1991年

  30. 岩体の透水特性の計測評価に関する研究 競争的資金

    制度名:Grant-in-Aid for Scientific Research

    1989年4月 ~

  31. 地殻応力の計測評価に関する研究 競争的資金

    制度名:Grant-in-Aid for Scientific Research

    1989年4月 ~

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社会貢献活動 1

  1. みやぎ県民大学

    2009年9月18日 ~

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    宮城県の県民を対象とする生涯学習活動支援の一環として講座「流れを科学する」の「地下のながれ」を担当

その他 11

  1. コア変形法による地殻応力評価法

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    地殻空間の利用ならびに地球物理に関わる諸現象の解明には地殻に作用する応力を定量的に評価できることは必要である。また、応力成分の内の水平面内に作用する最小値については、その評価手法が確立している。しかしながら、最大値については特に大深度に適用できる実用的手段は未だにない。本研究は、コアの変形を利用して、この課題解決を目指すものである。

  2. 大深度地殻応力の定量評価

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    海底掘削孔内での高精度・高忠実度な性能をもつ応力・歪・傾斜・地震等の計測を可能にするため、陸上掘削孔で共同試験観測を行い、IFREEおよび東北大学の持てる技術・ノウハウを集結して比較検討・評価を行うことを目的とする。

  3. 人工未固結堆積物試料内におけるフラクチャ形成・進展と流体挙動に関する実験

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    人工未固結堆積物試料内におけるフラクチャ形成・進展と流体挙動に関する実験

  4. 人工未固結堆積物試料内におけるフラクチャ形成・進展実験

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    人工未固結堆積物試料内におけるフラクチャ形成・進展実験

  5. 堆積軟岩層を対象にした応力環境評価技術の開発

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    堆積軟岩層を対象にした応力環境評価技術の開発

  6. AEに基づく葛根田地熱貯留層内の流体移動評価に関する研究

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    AEに基づく葛根田地熱貯留層内の流体移動評価に関する研究

  7. 深部地殻応力評価のためのBABHYシステムの開発に関する研究

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    深部地殻応力評価のためのBABHYシステムの開発に関する研究

  8. 火山噴火解明のためのマグマき裂進展に及ぼす熱応力の影響に関する研究

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    火山噴火解明のためのマグマき裂進展に及ぼす熱応力の影響に関する研究

  9. AEに基づく先進地熱貯留層内の圧力と流体移動マッピング技術に関する研究

    詳細を見る 詳細を閉じる

    AEに基づく先進地熱貯留層内の圧力と流体移動マッピング技術に関する研究

  10. 冷却に伴うき裂透水性の変化挙動に関する研究

    詳細を見る 詳細を閉じる

    冷却に伴うき裂透水性の変化挙動に関する研究

  11. 地下き裂の透水性と地殻応力との関係に関する研究

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    地下き裂の透水性と地殻応力との関係に関する研究

︎全件表示 ︎最初の5件までを表示