页岩气渗流特征及压裂井产能

依据分子运动学理论，对含纳米孔隙页岩储层气体渗流规律进行理论分析，建立适用于多尺度介质的气体运动方程和页岩气输运数学模型，得到径向流条件下的压力分布公式，形成页岩气井控制区域计算方法，建立了压裂井三区耦合非线性渗流产能方程.采用牛顿迭代法进行数值计算，研究分析了生产压差、裂缝半长、裂缝导流能力、扩散系数等参数对页岩气井产量的影响.计算结果表明:气井产量随扩散系数的增大而增大，对于含纳米孔隙的页岩储层中扩散效应对气井的产量贡献不容忽视；在一定的储层和生产条件下，气井产量随裂缝半长的增大而先快速增大后趋于平缓，因此存在一个最佳范围，各参数应进行定量的、合理的优化配置. 

Characteristics of gas flow and productivity of fractured wells in shale gas sediments

Based on the molecular kinetic theory, the gas seepage law was analyzed in shale gas sediments with nanopores. The motion equation and transport mathematical model of shale gas were established which were suitable for multi-scale media. The pressure distribution formula under radial flow was derived, and a new method to calculate the control area of shale gas wells was formed. The non-linear productivity equation of fractured wells was presented with three-region division. Some parameters, such as production pres-sure difference, fracture half-length, fracture conductivity and diffusion coefficient, which can influence the gas well production were analyzed according the numerical calculation of the Newton iteration method. It is shown that the gas well production increases with increasing diffusion coefficient, and the contribution of diffusion effect to production should not be ignored for shale gas reservoirs with nanopores. In a certain reservoir and production conditions the gas well production increases with the increase of fracture half-length, but the increase rate is slower. Thus there is an optimum combination of parameters for shale gas development.