Predicting long‐term production from gas shale reservoirs is a challenging task due to changes in effective stress and permeability during gas production. Unlike coal, the variation of sorbing gas permeability with pore pressure in shale does not always feature a biphasic trend under a constant confining pressure. The present contribution demonstrates that the biphasic dependence of permeability on pore pressure depends on a number of physical and geometrical factors, each with a distinct impact on gas permeability. This includes pore size, adsorption isotherm, and the variation of gas viscosity with pore pressure. A single‐capillary model is proposed for the apparent permeability of real gas in shale. Results indicate that the biphasic relation between apparent permeability and pore pressure is prevalent when the sorbing gas flows in sufficiently small pores. In addition, the effects of sorption isotherm and internal resistance of nonideal gas to flow cannot be ignored.

中文翻译：

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页岩气藏纳米孔表观渗透率的应力依赖性模型

由于天然气生产过程中有效应力和渗透率的变化，预测天然气页岩储层的长期产量是一项艰巨的任务。与煤不同，页岩中吸附气体渗透率随孔隙压力的变化在恒定围压下并不总是具有两相趋势。本研究表明，渗透率对孔隙压力的双相依赖性取决于许多物理和几何因素，每个因素对气体渗透率都有明显的影响。这包括孔径，吸附等温线以及气体粘度随孔隙压力的变化。针对页岩中真实气体的表观渗透率，提出了单毛细管模型。结果表明，当吸附气体在足够小的孔隙中流动时，表观渗透率与孔隙压力之间存在两相关系。另外，吸附等温线的影响和非理想气体的内部流动阻力也不能忽略。