Coupled 4D Flow-Geomechanics Simulation to Characterize Dynamic Fracture Propagation in Tight Sandstone Reservoirs.

Although China's low-permeability and tight oil reservoir utilization and newly proven reserves are growing annually, the overall recovery of such reservoirs is generally low. One of the main factors influencing the low recovery is the effect of intricate dynamic fracture propagations on the remaining oil distribution. Constrained by the evolution of an in situ stress field and the accumulation of fluid injection volumes, the growth of dynamic fractures allows a production profile of water breakthrough. To reveal this phenomenon, this paper systematically summarized the workflow of geoengineering integration and took the target block of an oil reservoir in the Changqing oilfield as an example. The numerical simulation model and geomechanical model of the reservoir were established, respectively, by using core analysis and rock mechanics experiments, and the simulation of dynamic fracture propagation under the control of flow-geomechanical coupling mechanisms was carried out. It is found that injection-induced fractures open and propagate under propulsion pressure until they link with natural fractures when the injection pressure surpasses the formation rupture pressure. The natural fractures become effective after long-term water injection and propagate until they connect to hydraulic fractures near a producing well. The study results on the dynamic fracture propagation process have theoretical and practical implications for the characterization of fractures, residual oil production, and water control techniques in tight sandstone reservoirs.