首页|COMPARISON OF SHEAR AND TENSILE FRACTURE PERMEABILITY IN GRANITE UNDER LOADING-UNLOADING STRESS CONDITONS
COMPARISON OF SHEAR AND TENSILE FRACTURE PERMEABILITY IN GRANITE UNDER LOADING-UNLOADING STRESS CONDITONS
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NSTL
It is of great significance to evaluate the fracture permeability after reservoir stimulation for geothermal extraction. This paper is focused on evaluating the permeability of two kinds of fractures-shear and tensile fracture generated by mechanical force in a laboratory. It is found that the permeability of tensile fractures is 1.5-3.5 times as much as the shear fracture under loading and unloading stress from 1 to 60 to 1 MPa. Both shear and tensile fractures experience a relative high permeability reduction (i.e., up to 99%) under loading stress, while the absolute permeability reduction of a shear fracture is much lower than that of a tensile fracture. The tensile fracture experiences a much higher absolute permeability enhancement under unloading stress. When it comes to the whole loading and unloading cycle, shear fracture has a lower absolute but a higher relative permeability reduction. Three models (i.e., the exponential, power, and Walsh models) were used to evaluate the stress dependence of permeability. In total, the stress sensibility of permeability in loading stress is higher than that in unloading stress. And this sensibility for shear fractures is higher than that of tensile fractures in loading stress while it is lower than that of tensile fractures in unloading stress, which causes the higher relative permeability reduction in shear fractures. The suitability check of the models shows that the exponential model is not suitable for data under unloading stress, the Walsh model has a better suitability for data under loading stress than that under unloading stress, and the power-law model is suitable for data under both loading and stresses.
shear and tensile fracturespermeabilityloading and unloadingstress dependenceHYDRAULIC CONDUCTIVITYCONFINING PRESSUREPORE PRESSUREFLOW BEHAVIORFLUID-FLOWROCKSTIMULATIONGENERATIONMODEL
Su, Xiaopeng、Liu, Jialiang、Liu, Hejuan、Zhou, Lei、Chen, Junchao、Li, Honglian
NSTL
