双重介质煤层气-水两相不稳定试井模型

Gas-water two-phase unsteady well testing model of dual porosity media in coal bed

为了明确煤层气排采时的渗流过程,考虑煤层气在生产过程中的气-水两相分布,提出一种双重介质煤层气-水两相不稳定试井模型。利用基于Delaunay网格的有限体积法对模型进行求解,得到了双重介质煤层气-水两相试井理论曲线,并分析了模型在不同地质参数情况下的双对数曲线的特征。结果表明:基质储能系数越大,对生产越有利。含气饱和度越大,到达复合半径的时间越早,达到系统稳定所需的时间越长;解吸系数越大,表现为边界距离的增大,有利于煤层气长期稳定生产。

To clarify the seepage process of coalbed methane(CBM)during producing,a unsteady well testing model of dual porosity considering the permeability relationship of gas and water was proposed.The model was solved by finite volume method(FVM)on Delaunay to gain the type curves,and the characteristics of different parameters were analyzed.The results show that the larger storage coefficient of matrix is,the better for production.The greater the gas saturation is,the earlier it gets to the complex radius and the longer it takes to achieve system stability.The larger the desorption coefficient shows the increasing boundary distance,and it is good for stable production in the long time.