考虑自调节效应的煤层气动态渗透率模型

Dynamic permeability model considering self?鄄adjustment effect for coalbed methane

赵明章 姚泽 徐明 李健 徐九华

北京科技大学土木与环境工程学院，北京 100083 中国石油天然气勘探开发公司，北京 100034 中海油研究总院，北京 100027 中国石油集团渤海钻探工程有限公司测井分公司，天津 300280

School of Civil and Environment Engineering, Beijing University of Science and Technology, Beijing 100083, China China National Oil and Gas Exploration and Development Corporation, CNPC, Beijing 100034, China CNOOC Research Institute, Beijing 100027, China Logging Company, Bohai Drilling Engineering Co. Ltd., CNPC, Tianjin 300280, China

在煤层气开采过程中，煤层的自调节效应将导致煤层渗透率发生显著变化。根据固体表面能与固体变形理论，建立了考虑自调节效应的煤层动态渗透率数学模型。结合Ji?鄄Quan Shi模型，消除了煤体积收缩系数和弹性模量取值对计算结果准确性的影响，使计算结果更接近煤层的真实情况。实例计算结果表明：文中所建模型比Ji?鄄Quan Shi模型的计算误差小，更接近煤层实际；煤层自调节效应引起的煤层渗透率变化量，随煤层压力的降低呈指数递增；随着泊松比的增大，煤层渗透率的增量减小；煤层气中Langmuir体积大的气体浓度越大，气体组分对煤层渗透率的变化影响越大。

During the production of coalbed methane, the permeability of the coal layer changes significantly because of its self?鄄adjustment effect. In this paper, according to surface energy theory and deformation theory of solid, the mathematical model of dynamic permeability of coal bed was built up with considering self?鄄adjustment effect of coal bed. Combined with Ji?鄄Quan Shi model, the influence of coal volume shrinkage coefficient and elastic modulus on the accuracy of the calculated result is eliminated and the result will be more concordant with the reality of the coal layer. The results of case study show that the calculated errors of the model built up in this paper are smaller than the errors of Ji?鄄Quan Shi model and it is more concordant with the reality of coal layer. The permeability change of coal bed, which is caused by self?鄄adjustment effect of coal layer, increases exponentially with the decrease of pressure of coal bed. With increasing of Poisson ratio, the increment of coal bed permeability goes down. The higher concentration of the gas with large Langmuir volume is, the greater influence on the change of coal layer permeability is.

10.6056/dkyqt201301015