变形介质煤层气压力动态特征分析

Analysis of pressure performance of coal-bed methane through deformable medium

在考虑煤层渗透率应力敏感性的基础上,采用非平衡态吸附模型,研究单相煤层气在煤体和割理中的流动规律。在拟稳态流数学模型假设条件下,用气体拟压力代替Langmuir吸附公式中的压力,得到气层中拟压力所满足的方程,并采用正则摄动法和Laplace变换法进行求解,通过拉氏数值反演,得到0阶摄动解。对渗透率变异系数和双重介质参数变化时压力的变化规律进行了分析,该结果为煤层气藏开发提供了理论依据和新的试井模型。

Based on consideration of stress sensitivity of coal seam permeability,the single-phase flow rule of coal-bed gas in coal and cleats is studied by using non-equilibrium adsorption model.Under the assumption of mathematical models of pseudo-steady flow,the equation meeting the needs of pseudo-pressure in coal-bed gas layer is obtained by replacing the pressure in Langmuir adsorption formula with pseudo-pressure of gas.The models may be solved by use of regular perturbation method and Laplace transform,and the zero-order perturbation solution can be obtained through numerical inversion.This paper also discusses the change rule of pressure along with the changes in permeability deformation coefficient and dual media parameters.These results have provided a theoretical basis and new well-testing model for coal-bed methane reservoir development.