Evolution of rock fracture permeability in coupled processes with variable temperatures

The projects in deep rock are under complex geological environment of high stress, high water pressure, high heat, etc. These factors may have important influences on the permeability in fractured rock and further on the safety and productivity of deep rock projects. Flow-through tests on an artificial fracture in limestone are conducted at 25℃~90℃. The effects of different temperatures on the evolution of permeability in fractured rock are studied. The results show that at the initial stage of heating, the flow has a peak under constant effective stress. It decreases slowly until one steady count at constant temperature at last. The fracture permeability declines monotonically with the increasing temperature under constant effective stress. Faster speeds of fracture closure at the initial stage, shorter time required for stabilization and smaller aperture at the final equilibrium under higher temperatures can also be observed. The solubility speed and dissolved mineral matter of limestone increase with the increasing temperatures.