低渗–致密气藏压裂井产能理论计算方法

Study on Productivity Calculation Model of Fractured Well in Low Permeability-Tight Gas Reservoir

摘要: 目前越来越多的低渗致密气藏投入开发，但由于自然产能低，需人工压裂。很多学者针对低渗压裂井产能进行了研究，但并没有学者同时考虑低渗致密气藏储层存在的应力敏感性、气体通过低渗致密多孔介质同样具有启动压力梯度以及人工裂缝近井地带存在高速非达西效应等因素对产能的影响，因而计算结果往往偏大。本文以扰动椭圆以及发展的矩形族思想为基础，理论推导出考虑因素更全面的低渗致密气藏压裂井产能理论计算公式，并绘制了相应的产能曲线。研究表明，拟启动压力梯度、变形介质系数、高速非达西渗流因子以及裂缝参数均对低渗致密气藏压裂井产能有影响，并绘制了单因素敏感性分析图版，研究结果具有较高的理论价值和实践指导意义。

Abstract: With the development of more and more low-permeability tight gas reservoir, hydraulic fracturing is needed due to the low natural productivity. Productivity of low permeability fractured well has been studied by many scholars, however, the calculation result is usually large while the influencing factors of productivity are not simultaneously considered, including the stress sensitivity, threshold pressure gradient with gas flow and high-speed non-Darcy effect of hydraulic fracture near the well. In this paper, on the basis of disturbing ellipse and rectangular family, the productivity calculation formula of fractured well in low permeability tight gas reservoir is derived theoretically with consideration of more factors and the corresponding productivity curve is plotted. Result shows that, the influencing factors of fractured well productivity in low permeability tight gas reservoir include threshold pressure gradient, deformed media coefficient, high-speed non-Darcy flow factor and fracture parameters. Single factor sensitivity analysis plate is also protracted, which has important theoretical value and practical meaning.