Semi-analytical seepage model for horizontal wells with volume fracturing in tight oil reservoirs

Due to special geologic conditions, complex fracture network may be created in unconventional oil reservoir during large-scale hydraulic fracturing, which may lead to changes in seepage pattern in such reservoirs. Based on accurate description of such complex fracture network using volumetric source function, semi-analytical seepage model for horizontal wells stimulated by volume fracturing in tight oil reservoir has been built with consideration of permeability in the fracture network. Modeling results coincide well with numerical simulation results for these reservoirs. Calculation results show seepage flow in oil reservoirs with complex fracture network can be classified into following 6 phases: linear flow, supplying flow, transitional flow, dual radial flow, late-stage radial flow and border-controlled flow. Permeability in the fracture network may predominantly affect linear flow and supplying flow in early stages, while permeability in secondary fractures may dramatically affect supplying flow. At the same time, transitional flow, dual radial flow and late-stage radial flow are significantly subject to impacts of geometric sizes of complex fracture networks. The newly developed model may be applied to predict productivity, highlight seepage pattern and assess performances of horizontal wells stimulated by volume fracturing.