【摘要】 由于煤层气开采过程中,煤体容易变形,传统的煤层气井各种测试问题的数学模型都假设渗透率为 常数,这对于变形介质煤层的压力空间变化和瞬时变化将产生较大误差.通过考虑煤层的双重介质特征和煤层气 的吸附特征及介质的变形,引入渗透率模数建立了变形双重介质非稳态渗流模型。渗透率依赖于孔隙压力变化的 流动方程是强非线性的,对于双重介质非稳态渗流模型采用正则摄动法和Laplace变换进行求解,并通过拉氏数值 反演得到零阶摄动解。对变形参数和双重介质参数变化时压力的变化规律进行了讨论,用新模型绘制的典型压力 曲线将得到更加准确的结果,这些结果为煤层气藏开发提供了理论依据和新的试井模型。更多还原

【Abstract】 Because the coal body is easy to be deformed in the course of coalbed methane well production and the permeability has been assumed to be a constant in the conventional mathematical models of solving various coalbed methane well test problems, a relative great influence will exert on the spacial and instantaneous changes in pressure of deformation media——coal bed. In considerastion of the characteristics of coalbed’s dual media, coalbed methane adsorption and medium deformation, an unsteady percolation flow model of deformed dual media was set up by introducing the permeability module. Owing to the fact that the flow equation of permeability’s depending on the change in pore pressure is of strong nonlinearity, the model may be solved by use of regular perturbation method and Laplcae transform and the zero-order perturbation solution can be obtained through Laplace numerical inversion. In the paper, the change rule of pressure along with the changes in the deformation and dual media parameters is discussed, and it is pointed out that more accurate results will be achieved by use of the typical pressure curves drawn up through the new model. All of these results have provided a theoretical basis and new well test model for coalbed methane reservoir development.更多还原