HR: 0800h
AN: T51A-1325    [Abstracts]
TI: Pressurization effect on bulk properties and pore connection of sedimentary rock specimens from TCDP cores
AU: * Takahashi, M
EM: miki.takahashi@aist.go.jp
AF: Institute of Geology and Geoinformation, AIST, 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AU: Kitamura, K
T51A-1325 AF: Institute of Geology and Geoinformation, AIST, 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AU: Masuda, K
T51A-1325 AF: Institute of Geology and Geoinformation, AIST, 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AU: Ito, H
T51A-1325 AF: CDEX, JAMSTEC, 3173-25 Showa-machi, Kanazawa-ku, Yokohama, 236-0001 Japan
AU: Song, S
T51A-1325 AF: National Taiwan Univ., No.1, Sec. 4, Roosevelt Road, Taipei, 106 Taiwan
AU: Wang, C
T51A-1325 AF: National Central Univ., No.300, Jhongda Rord, Jhongli City, Taoyuan, 32001 Taiwan
AB: To understand the fault rock behaviors in seismic - aseismic periods, there are many important physical properties of rocks observed in the laboratory such as frictional strength, elastic wave velocity and permeability. It has been difficult to monitor these properties multiply in one test. Last year, we improved our triaxial testing machine at the AIST to be able to measure the elastic wave velocity and the permeability simultaneously during the runs. We had here an opportunity to use TCDP core samples that penetrated the Chelungpu Fault, the source of the 1999 Chi-Chi earthquake in Taiwan to reveal the water effect on the velocity and the permeability. We obtained 18 experimental specimens sampled from 482 m to 1316 m depth of TCDP boreholes. It would be the first report to refer a relation between these physical properties of porous sediments. The confining pressure condition was 30 MPa constant but the pore water pressure was decreased from 20 MPa to 0 MPa during the measurements. Thus, the effective pressure was increased from 10 MPa to 30 MPa. At every 5 MPa during the pore pressure changes, the elastic wave velocity and permeability were measured simultaneously. Detail on the velocity data will presented by co-author K. Kitamura. The permeability were ranged from 10^-13 m² for clean-sandstone to 10^-17 m² for silty-sandstone under 25 MPa of the effective pressure. Increment of the velocity with increasing the effective pressure was observed under 20 MPa of effective pressure before showing constant value over 20 MPa which corresponds to the over pressure condition. Because the velocity data reflects the bulk density, the increment of the rock density will be saturated under the over pressure conditions. On the other hand, the permeability was decreased logarithmically with increasing the effective pressure in this experimental range. It can be said the pressurization effect on elastic wave velocity would reflect significantly on the bulk density of the skeletal sedimentary rock, while that on permeability would reflect the size of connections of pore network.
DE: 5100 PHYSICAL PROPERTIES OF ROCKS
DE: 5112 Microstructure
DE: 5114 Permeability and porosity
DE: 5139 Transport properties
DE: 5194 Instruments and techniques
SC: Tectonophysics [T]
MN: Fall Meeting 2005