THE ADVANCED EMBEDDED DISCRETE FRACTURE MODEL CONSIDERING THE CAPILLARY PRESSURE DIFFERENCE

Hydraulic fracturing is a widely used technique to produce several conductive fractures in low-permeability reservoirs resulting in the improvement of production. The embedded discrete fracture model has received considerable attention to simulate the flow in fractured reservoirs due to its low cost. In low-permeability reservoirs with conductive fractures, there is a large capillary pressure difference between matrix and fracture. This difference may cause the pressure and saturation to change very sharply near matrix-fracture interfaces. However, it is difficult to calculate the matrix-fracture transfer flux accurately for the traditional embedded discrete fracture model. According to the recent research conclusion, three flow patterns can be distinguished for two-phase steady flow across the matrix fracture interface. In this article, a modified embedded discrete fracture model is proposed, in which the one-dimensional analytical solution is employed to construct the numerical scheme of calculating the matrix fracture transfer flow. Numerical tests show that the simulation results of the proposed embedded discrete fracture model are in agreement with the reference solution, in spite of the degree of the capillary pressure strength in the matrix. In contrast, the accuracy of the traditional embedded discrete fracture model depends on the degree of the capillary pressure strength in the matrix.