关键词:

"> 流固耦合, 水力压裂, 裂缝扩展, CDEM, 砾岩

Abstract:

Large-scale hydraulic fracturing is the essential technology for cost-effective and efficient development of tight sandy conglomerate reservoirs. Gravel parameters are considered the key factors that influence the hydraulic fracture geometry. The existence of gravels can make it even harder to complete fracturing stimulation. The complex fracture geometry，high tortuosity，and shorter supporting fracture length make it difficult to achieve the designed fracture conductivity. In this research，the continuous-discontinuous element method （CDEM） was applied to establish a 2D full fluid-solid coupling fracture propagation model to explore the influence of stress difference，gravel content，and flow rate on the fracture propagation geometry. The numerical simulation results show that：the multi-phase media hydraulic fracturing model based on the CDEM method can accurately simulate the overall fracture propagation geometry under the influence of gravel；the fractures will divert and generate a tortuous fracture when meeting high strength gravel；in reservoirs with high stress，hydraulic fractures tend to pass around the gravel and then divert to the direction of the maximum horizontal principal stress；in the presence of gravel，the fracture propagation will shape a high-pressure zone and generate more micro-fractures，thus increasing the stimulated reservoir volume. This study lays a theoretical basis for optimization of the fracturing design of conglomerate reservoirs.

Key words:

"> fluid-solid coupling, hydraulic fracturing, fracture propagation, CDEM, conglomerate