Productivity evaluation of horizontal wells in Sulige tight gas reservoir with strong heterogeneity

While horizontal wells(HWs)development have achieved excellent performance in Sulige Gasfield, there exist practical problems including difficulty in productivity evaluation and uncertainty in determining effect factors of productivity. Based on the analyses of previous materials and data of field, this paper proposed an absolute open flow single-point equation and rapid well-controlled reserves evaluation chart for HWs and evaluated productivity of early production wells. Then main effect factors of productivity are filtered by defining productivity parameters of single fracture and unit formation thickness. Results show that it takes 100 to 600 days for horizontal wells to enter the boundary controlled flow period due to poor properties and strong heterogeneity of Sulige tight gas field. The absolute open flow rate of wells concentrates between 10×104m3/d and 50×104m3/d with an average of 25. 7×104m3/d. The well-controlled reserves of HWs range from 4 000×104m3 to 8 000×104m3 with an average of 7 784×104m3. The production capacity of horizontal well is high though it shows great difference for individual wells. Both geological and engineering factors affect HWS productivity. Specifically, the most influential geological factor is formation thickness, then, is gas saturation. The effect of porosity is slight and that of permeability is difficult to determine. Among engineering factors, effective length of horizontal wells, fracturing segments, and fracturing scale affect productivity more greatly than flowing back ratio of fracturing fluid. ©, 2015, Science Press. All right reserved.