The interplay between natural fractures and stress as controls to hydraulic fracture geometry in depleted reservoirs

Abstract

Pressure changes in the reservoir due to injection or production, lead to anisotropic changes in the magnitude and orientation of the stresses in the reservoir. The characteristics of the modified stress field can potentially lead to asymmetric fracture growth in infill wells stimulated by hydraulic fracturing, which in turn could potentially cause a detrimental interference between wells. The final geometry of the hydraulic fractures, however, will depend on the relative contributions of several other variables and not on changes in stress alone. Therefore, for the planning and optimization of infill wells, the interplay among these variables must be accounted for. In this paper we study via numerical simulations, the relative weight of rock fabric and depletion-induced stress in relation to the geometry and propagation of hydraulic fractures near a producing well. Our results indicate that the presence of a dense network of natural fractures can override the effect of depletion-induced stress, and limit the asymmetric growth of the fractures.