| Title | Coupled Mechanical and Hydraulic Laboratory Experiment of Shearing on Granite Fracture |
|---|---|
| Authors | Takuya Ishibashi and Hiroshi Asanuma |
| Year | 2018 |
| Conference | Asian Geothermal Symposium |
| Keywords | EGS, rock fracture, laboratory experiment, shearing, permeability, acoustic emission |
| Abstract | Hydraulic stimulation on the geothermal reservoir is the well-known operation for improving the transmissivity and fracture connectivity within the reservoir. In this operation, by increasing pore pressure, shear slip on pre-existing fractures are triggered or new fractures generate from the tips or the middle of pre-existing fractures. Thus, the mechanical and hydraulic properties of fracture/fracture network are strongly coupled during the stimulation, but it is not well quantified how these properties are coupled. Here, we conduct the laboratory experiments to concurrently monitor the mechanical and hydraulic properties during the hydraulic shearing of rock fracture, which is similar to the naturally observed fracture having rough surfaces, at high stress state. Through the experiments, we find the shear slip is limited to 0.16% of the representative length of pressurized area, and the fracture permeability increases about 8 times of the initial permeability (before slip). Interestingly, fractures are newly propagated from the middle of the pre-existing fracture’s surface and these fractures possibly have significant roles on both mechanical and hydraulic properties of the fracture. |