A Numerical Evaluation of the Geomechanical Interactions Between a Hydraulic Fracture Stimulation and a Natural Fracture System

摘要

Due to the low permeability of many shale gas reservoirs, multi-stage hydraulic fracturing in horizontal wells is used to increase the stimulated volume. However, each created hydraulic fracture alters the stress field around it, and subsequent fractures are affected by the stress field from the previous fractures, which results in higher net pressures, smaller fracture widths, and diminished microseismic emissions. The results of a numerical evaluation of the effect of stress shadowing, as a function of natural fracture and geomechanical properties, are presented, including a detailed evaluation of natural fracture shear failure (and, by analogy, the microseismicity) due to a created hydraulic fracture using both continuum and discrete element modeling approaches. The results show the critical impact that a created hydraulic fracture has on the shear of the natural fracture system, which in-turn, significantly affects the success of the stimulation. Furthermore, the results provide important insight into the mechanisms that generate the microseismicity that occurs during a hydraulic fracture stimulation.