| 講演要旨(和文) | | 岩石試料への高圧水の浸入に伴う、岩石内部のクラック形状(アスペクト比)と水の飽和度の変化を,Vp,Vs,歪の測定値をもとに計算した.岩石試料への流体浸入に起因する割れ目の性状変化や飽和度を知ることは,地下亀裂の性質を知る上で重要である.CCSなど地下への流体注入時のモニタリングデータの解釈にも有用である。花崗岩試料に封圧(30MPa)と破壊強度の約70%の差応力(350MPa)を加え,その後は応力状態を一定に保った.試料下端面から一定圧力(25MPa)で水を浸入させた.Vp,Vs,歪のデータを同時に満足するアスペクト比と飽和度の組を最小自乗法によって計算し,次の結果を得た.(1)試料に差応力を加えた状態でのクラックのアスペクト比は約1/400であった.(2)水の浸入に伴ってアスペクト比は1/400から1/220くらいまで変化した.(3)水の飽和度は約0.7まで変化した. |
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| | 講演要旨(英文) | | We estimated crack characterizations such as the aspect ratio and the degree of water saturation and their changes during the water migration into a granitic rock subjected to the confining pressure and the differential stress. We applied the differential stress of 370 MPa under the confining pressure of 30 MPa. We injected water from the bottom end surface of the sample. The pressure of water injection was held constant at 25 MPa. During the water migration, P-and S-wave velocities of elastic waves that propagated along the paths parallel to the top and bottom surfaces of the sample were measured. We also measured strains of the sample surface and monitored acoustic emissions, AE. We estimated the aspect ratio and the degree of water saturation by applying the cracked solid model to the data on P and S wave velocities and the crack density. We found, the aspect ratio of dry cracks before the water injection was 1/400, during the water migration, the aspect ratio changed from 1/400 to 1/220, and degree of water saturation increased up to 0.7. |
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