Sammendrag
Pore pressure reduction, caused by reservoir fluid production, will alter the stresses in the vicinity of a producer. These stress alterations affect the propagation of hydraulic fractures that originate e.g. during water or polymer injection into injector wells as part of enhanced oil recovery (EOR) or improvement of geothermal well productivity. In this study, we use a modified discrete element model (MDEM), coupled to the fluid-flow simulator Tough2, to investigate how hydraulic fractures are affected when growing into a zone of altered pore pressure. The study shows that flow induced stress changes can have a significant effect on hydraulic fracture propagation. Hydraulic fractures tend to bend around the producer, and the degree of deviation from the far stress field is dependent on several factors, including production rate, time, reservoir permeability, stress anisotropy and Poisson’s ratio. The stress alterations show a high sensitivity to stress anisotropy and are also affected by Poisson’s ratio.