页岩气藏压裂水平井产能模型及影响因素

Productivity model of fractured horizontal wells in shale gas reservoirs and analysis of influential factors

由于页岩气在储层中存在解吸、扩散和渗流相互作用,使页岩气藏压裂水平井与常规气藏压裂水平井在渗流特征及产能递减规律方面有较大差异.综合考虑页岩气解吸、扩散和渗流特征,建立页岩气藏压裂水平井产能模型,应用Laplace变换和Duhamel原理,结合Stehfest数值反演求解产能模型,绘制页岩气藏压裂水平井产能递减曲线,分析解吸系数、无因次储容系数、无因次解吸时间、无因次人工裂缝间距、人工裂缝条数和裂缝表皮系数对产能递减曲线的影响.该结果对认识页岩气藏压裂水平井产能递减规律、评价预测产能及优化压裂裂缝提供参考.

Due to the effects of desorption,diffusion and seepage,the seepage characteristic and productivity decline law of fractured horizontal wells in shale gas reservoirs are different from the ones in conventional gas reservoirs.Therefore,according to the characteristic of desorption,diffusion and seepage,a productivity model of fractured horizontal wells in shale gas reservoirs has been established.Laplace transform and the principle of Duhamel in combination with Stehfest numerical inversion algorithm are used to solve the model.The productivity decline curves are plotted and the influence of the desorption coefficient,the dimensionless storability ratio,the dimensionless desorption time,the dimensionless fracture spacing,the number of fracture and the fracture skin factor on the productivity decline curves of fractured horizontal wells in shale gas reservoirs is analyzed.The results make it easier to understand the productivity decline law of fractured horizontal wells in shale gas reservoirs and provide the theoretical support for the productivity evaluation and the fracture optimization of fractured horizontal wells in shale gas reservoirs.