CO_2地下处置与煤层气开采的数值模拟

Numerical Simulation of CO_2 underground Sequestration and Exploitation of Coal Bed Methane

采用Crank-nisholson差分格式与Richtmyer方法,对单井注入CO2与CH4二组分气体的扩散渗流物理模型进行离散化处理,从而把对非线性微分方程组的求解转化为对线性方程组的求解。基于Matlab语言编制数值计算程序,同时依据永安、双柳和寺河三矿煤层的实际参数进行模拟计算,得到了注气过程中各组分气体分压和基质内组分浓度的变化规律。数值模拟计算表明,向煤层中注入CO2不仅可以驱替、置换煤层气,提高煤层气的回收率,而且煤层对CO2有一定的储存能力。

The diffusion-permeation physical model of CO2 and CH4 by single-well was discretized based on Crank-nisholson difference scheme, and then Richtmyer method was adopted to transfer the solving of nonlinear differential equations to the solving of linear equations. At last the changing rules of viscosity in the matrix and after-injection pressure and viscosity for different components were revealed from the Matlab Language Programing and the simulation computation to real reservoir parameters of three reservoir -- Yongan, Shuangliu and Sihe. The result of numerical simulation shows that CO2 can be injected into coal seam to displace the coal bed methane and to enhance recovery of the bed methane. Besides, CO2 can be stored in coal seam.