Integral equation solution of heat extraction-induced thermal stress in enhanced geothermal reservoirs

摘要

During fluid injection in enhanced geothermal systems, thermo-mechanical processes can play an important role. In fact, the phenomena of reservoir seismicity and the variation of injectivity with respect to injection water temperature can be attributed to the induced thermal stresses. In this paper, a three-dimensional integral equation formulation is presented for calculating thermally induced stresses associated with the cooling of a fracture in a geothermal reservoir. By utilizing Green's function in the integral equation, the three-dimensional heat flow and stresses in the reservoir are modelled without discretizing the reservoir. The formulation is implemented in a computer program for the solution of injection into an infinite fracture as well as for the injection/extraction in an arbitrarily shaped fracture.