By using a two-dimensional fluid-filled crack model, fracture characterization was attempted from microseimic events observed at the Hijiori and Ogachi HDR fields, Japan. In the model, the effects of fluid viscosity, rock permeability and stiffness due to partial contact between the upper and lower surfaces of the crack were taken into account. It is possible to estimate length, aperture and interfacial stiffness of a reservoir crack; the ratio of partial contact area to crack area can be estimated from the interfacial stiffness. In the case of the Hijiori field, the characterization was successful from two events. Crack length and aperture characterized from one of the two are about 11 m and 0.7 mm, respectively. Those from the other event are about 20 m and 35 mm, respectively. In the case of the Ogachi field, the characterization was successful from only one event. Crack length and aperture are about 50 m and 10 mm, respectively. The ratio of partial contact area for both fields is estimated to be no more than 0.2%. However, there remained many events for which characterization was not successful. For such events, the mechanism responsible for crack oscillation must be different from that employed in the present model.
|ジャーナル||Transactions - Geothermal Resources Council|
|出版ステータス||Published - 1999 12月 1|
|イベント||Global Geothermal Resources: Sustainable Energy for the Future - Reno, NV, USA|
継続期間: 1999 10月 17 → 1999 10月 20
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