Effect of fluid viscosity, permeability of rock and crack interfacial stiffness on dynamic response of a geothermal reservoir crack (penny-shaped crack model)

In order to clarify the dynamic response of a fluid-filled crack in the earth's crust, dynamic elastic response of a penny-shaped fluid-filled crack is studied, emphasizing the effect of fluid viscosity, permeability of rock and the stiffness due to contact between the asperities on the upper and lower surfaces of the crack. It is revealed that the eigen angular frequencies normalized by C_r/aC_r: S wave phase velocity, a : crack radius) are governed primarily by the crack interfacial stiffness. The aspect ratio, i. e., the ratio of the crack radius to the initial aperture of the crack, has only weak effects on the normalized eigen angular frequencies except for the case of a crack that is completely open initially. It is also revealed that, for larger crack interfacial stiffness, the normalized eigen angular frequencies become smaller with permeability and attenuation becomes stroger with permeability. When crack interfacial stiffness is absent, permeability has weak effect on the normalized eigen angular frequencies and intensity of attenuation.