Multi-fractures Drainage Response in Production of Fractured Horizontal Wells in Tight Sandstone Oil Reservoirs

Based on the theory of unsteady elliptical flow in porous media, coupling elliptic flow in a reservoir matrix with high-velocity non-Darcy flow in hydraulic fractures, a new productivity prediction model is presented for multi-fractured horizontal wells (MFHWs) considering multi-fracture drainage response, which includes stress interferences between multi-fracture in a tight sandstone oil reservoir. A reasonable solution of the theoretical model is obtained and verified by the case of a real tight sandstone oil reservoir. Through theoretical calculation, the response law of multi-fracture elliptical drainage is revealed, and the factors influencing productivity are analyzed. The results show that the response areas which are the affected areas of multi-fracture stress interferences influenced by multi-fracture elliptical drainage extend with the production time gradually, and the propagation speed of the minor axis is larger than the major axis, which leads to the flow pattern changing from elliptical flow to pseudo-radial flow. The neighboring drainage areas controlled by fractures will intersect, and mutual interference will occur. The effective drainage area decreases gradually, which causes the production rate to decline quickly. When the threshold pressure gradient is considered, the MFHW production rate decreases obviously. The fracture length has a greater impact on the production rate than flow conductivity. The researched results have practical significance to some extent on improving the flow theory of MFHW in tight sandstone oil reservoirs.