地应力对煤层渗透性控制作用的研究进展

作用在煤岩层上的地应力可以分为有效应力和孔隙压力，而煤层是由孔隙和裂隙组成的双孔隙岩层。煤层气在煤层孔隙中遵循吸附解吸和扩散理论，在裂隙中遵循达西渗流理论，在低压状态下还受到滑脱效应的影响。通过论述应力加载路径、有效应力、孔隙压力以及滑脱效应与煤层渗透性的关系，找出不同应力状态下影响煤层渗透性的主要作用机制，并进一步论述了渗透率预测的经验模型和理论模型。经验模型是通过统计分析，建立实验数据或地质参数与渗透率的关系；理论模型是在一定的物理简化基础上，基于现有的渗流理论、应用力学和数学方法，推导出渗透率预测的基本公式。指出非线性渗流、渗流应力耦合、实验分析与数值模拟相结合是研究的主要方向。

Research progress on control of crustal stress on permeability of coal seam

The crustal stress on the coal and rock strata can be divided into effective stress and pore pressure.Coal reservoir is double porosity rock composed of pores and cracks.Coalbed methane in pores follows the adsorption-desorption theory and diffusion theory，follows Darcy′s law in cracks.In the low pressure state，coalbed methane is influenced by the Klinkenberg effect.By discussing the relationship between stress loading path，effective stress，pore pressure，the Klinkenberg effect and permeability of coal seam，the main action mechanisms of coal seam permeability under different stress states were found out.The empirical model and theoretical model of permeability prediction were further discussed.The empirical model establishes relationship between experimental data or geological parameters and permeability through statistical analysis.Based on a certain physical simplification，using the existing percolation theory，the theoretical model applies mechanics and mathematical methods to deduce the basic formula of permeability.It was pointed out that nonlinear seepage，seepage-stress coupling，the combination of experimental analysis and numerical simulation were the main research directions in the future.