论文部分内容阅读
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。
How to improve the CBM permeability is an important issue in the study of CBM exploitation. Based on the mathematic model of gas seepage law in coal seam, the COMSOL Multiphysics software was used to simulate the variation of desorption and seepage of non-isothermal CBM under the condition of flow-solid-heat coupling. The results show that under the condition of injection heat, the seepage pressure of coalbed methane decreases with the increase of temperature, and the descending speed is aggravated. The larger the pressure difference, the faster the seepage velocity of gas from high pressure area to low pressure area. The gas flows radially to the wellhead in the coal seam, and the gradient of the pressure near the wellhead increases and the gas seeps faster. In the area not affected by the heating, the CBM is not affected by the applied heat and the CBM desorption rate remains unchanged. Coal seam temperature increases, can speed up the seepage velocity of coalbed methane, improve permeability, increase coalbed methane production. The research results can provide the corresponding theoretical basis for the engineering practice of coalbed methane injection heat extraction of coalbed methane.