Geomechanics of hydraulic fracturing microseismicity: Part 2. Stress state determination

摘要

We investigate the hydraulic fracturing process by analysis of the associated microseismicity. In part 1, we recognized double-couple and hybrid microseismic events and their fault plane orientations. Critical stress (instability) and stress inversion techniques were used to assess fracture activation conditions. In part 2, we apply results from the tensile source model to investigate how activated faults relate to the stress state and geologic setting. We assess potential mechanisms for induced microseismicity including leakoff and diffuse pressurized fracture network flow, stress shadowing adjacent to large parent hydraulic fractures, and crack tip stress perturbations. Data are from the Mississippian Barnett Shale, Texas, and include microseismic events from sequential pumping stages in two adjacent horizontal wells that were recorded in two downhole monitor wells, as well as operations, wellbore-derived stress, and natural fracture data.