| Title | Experimental Evaluation of Fluid Flow through Artificial Shear Fracture in Granite |
|---|---|
| Authors | Watanabe, Noriaki; Hirano, Nobuo; Tsuchiya, Noriyoshi |
| Year | 2006 |
| Conference | Geothermal Resources Council Transactions |
| Keywords | Enhanced Geothermal Systems; fluid flow, permeability, shear fracture, granite, flow-through experiment, direct shear test, fracturing, coupling, stress, flow, EGS |
| Abstract | Direct shear tests were performed for intact granite samples to prepare specimens containing single shear fractures created under 20, 40, 60 MPa normal stress and 1, 3, 5 mm shear displacement conditions, for flow-through experiments. Shear fractures were successfully created on the constrained fracturing plane. Different normal stress and shear displacement conditions caused different roughness of fracture surfaces. Flow-through experiments were performed for the specimens containing shear fractures under 10-100 MPa confining pressure conditions. In the case of the shear fractures created under 20, 40 MPa normal stress and 1, 5 mm shear displacement conditions, no obvious differences were observed in permeability despite different normal stress and shear displacement conditions. Permeability decreased significantly under low confining pressure conditions (< 40-50 MPa), and then slightly decreased with increasing confining pressure. In the case of the shear fractures created under 60 MPa normal stress and 1, 3, 5 mm shear displacement conditions, on the other hand, permeability differed from the above case. It was observed that permeability decreased drastically under high confining pressure conditions (> 70 MPa). It was also observed that permeability increased clearly with increasing shear displacement condition. |