ABSTRACT:

This paper investigates the effects of fluid injection and heat extraction on pressure and temperature diffusion processes, and fracture/matrix deformation in an enhanced geothermal reservoir. The geometry of a single linear fracture in a 2D permeable rock matrix is chosen. Using an instantaneous point source solution, expressions are derived for the pore-pressure diffusion in the fracture and the reservoir. Moreover, heat transport within the fracture includes advection and conduction from the fracture walls, while heat transport in the reservoir includes only conduction and is assumed one dimensional and perpendicular to the fracture. Based on these assumptions, a Green’s function approach is used to find the two-dimensional solution for the pressure and temperature diffusion. A numerical example illustrates the time-dependent variation of each of the two variables; fluid pressure and temperature and their sensitivity to the fracture/formation properties. The resulting solutions can be used, amongst others, to study wellbore stability and in fracture propagation models to simulate secondary fracture propagation from the main fracture.

1. INTRODUCTION
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