煤层气开采的二维非平衡吸附模型

由于煤层气工业发展比石油工业晚，故很多方面的研究都借鉴了石油开采的理论，鉴于煤层气开采机理与石油开采有本质的区别，因此煤层气的数学模型相对较油气藏模型要复杂。文章在平衡吸附模型的基础上，进一步研究了煤层气开采的非平衡吸附模型。充分考虑了煤层气的流动特性，并结合煤层气的开采特点，首先根据物质平衡原理以及朗格缪儿等温吸附曲线，建立了煤层气开采的扩散模型；然后结合达西定律，建立了煤层气开采的渗流模型；同时考虑到煤储层特征建立了煤层裂缝的孔隙度和渗透率模型，结合边界条件，形成了完整的煤层气开采的二维非平衡吸附数学模型。

2-D NON-EQUILIBRIUM SORPTION MODEL OF COAL-BED GAS EXPLOITATION

Since the coal-bed gas industry develops after the petroleum industry, the study on coal-bed gas exploitation is immature and has to refer to the theory of petroleum exploitation. But there is essential difference between coal-bed gas and petroleum on exploitation mechanism, and the mathematical model of coal-bed gas reservoirs is more complicated than that of oil/gas reservoirs. Based on the equilibrium sorption model, the non-equilibrium sorption model of coal-bed gas exploitation is studied furthermore. Fully considering the flowing behavior of coal-bed gas, integrating characteristics of coal-bed gas exploitation, and according to the material balance principle and the Langmuir adsorption isotherm curve, the diffusion model of coal-bed gas exploitation is first developed. Then combining with Darcy's law, the percolation model of coal-bed gas exploitation is built. Meanwhile, considering the features of coal reservoirs, the porosity and permeability model of fractures is developed for coal reservoirs. With the boundary conditions, the mathematical model of 2-D non-equilibrium sorption is formed completely for coal-bed gas exploitation.