温度作用下煤层瓦斯解吸渗流规律数值模拟

Numerical Simulation for Desorption and Seepage Rules of Coal-bed Mathane Considering Temperature Conditions

如何提高煤层气渗透率是目前煤层气开采研究中的重要课题。基于煤层瓦斯渗流规律数学模型,利用COMSOL Multiphysics软件,对流-固-热耦合条件下的非等温煤层气解吸、渗流变化规律进行了数值模拟。结果表明,在注热条件下,煤层气渗流压力随着温度的增加而下降,且下降速度加剧,压力差越大,气体从高压区域流向低压区域的渗流速度越快。气体在煤层中径向流向井口,井口附近压力的梯度增大,气体渗流速度较快;在未受到加热影响的区域,煤层气不受外加热量影响,煤层气解吸速率保持不变;注热后煤层温度升高,可以加快煤层气渗流速度、提高渗透率、增加煤层气产量。研究成果可为煤层中注热开采煤层气的工程实践提供相应的理论依据。

Improving coal methane penetration is an important subject in the current research for CBM（Coal-bed mathane）exploration.This article is based on a mathematical model of coal seam gas seepage law,using COMSOL Multiphysics software to do the numerical simulation.The variation of non-isothermal CBM desorption and seepage under the condition of fluid-solid-thermal coupling.The simulation results show that the seepage pressure drops more obvious and the pressure difference is greater and the seepage speed of gas from the high pressure area to a low pressure zone is faster than general exploitation as the temperature increases under the condition of heat injection.The gas radially flows to the shaft in the coal-bed and the pressure gradient near the shaft increases and the gas flows faster.Coal-bed methane is not applied by heat and the coalbed methane desorption rate is unchanged under the condition of no heat injection.Rising injecting heat could promote the desorption of coal methane,improve the permeability,achieve the purpose of improving coal methane production.The research results could provide corresponding theoretical basis for engineering practices of exploiting coal methane by heat injection.