钻孔抽放瓦斯流固耦合分析及数值模拟

Analysis and numerical simulation of fluid-structure coupling of gas drainage from boreholes

钻孔抽放瓦斯是中国利用和治理煤层瓦斯最主要的方法。随着开采深度的加深,地应力场等因素对瓦斯渗流的影响越来越明显。基于对煤层瓦斯一系列的假设的基础上,考虑了地应力、煤层瓦斯压力变化对煤体骨架产生的变形的影响,推导出了孔隙率、渗透率的表达式。运用多孔介质渗流的基本定理和流固耦合的基本理论得出了瓦斯流固耦合控制方程。运用多物理场耦合分析软件对钻孔抽放下的瓦斯渗流场进行了模拟分析。得到了钻孔抽放条件下瓦斯压力的分布、不同的埋藏深度下以及不同的钻孔参数(抽放负压、钻孔半径)对瓦斯渗流场的影响。分析模拟结果可以对现场瓦斯抽放提供理论指导。

Gas drainage from boreholes is main method of utilization and management of Chinese coal seam gas.As the exploitation depth increases,stress field and other factors on the impact of gas seepage are increasingly apparent.Based on the basis of a series of assumptions of coal seam gas,porosity and permeability equations are described by considering stress,coal seam gas pressure change on the coal produced by deformation of the skeleton.The fluid-structure coupling equations are derived by using the basic theorem of porous media flow and the fluid structure coupling theory.The gas seepage field is simulated and analyzed by using multi-physics coupling analysis software.The effect of gas pressure distribution,different burial depths and different drilling parameters（drainage negative pressure,drilling radius） on gas seepage field is obtained.Analysis of simulation results can provide theoretical guidance for on-site gas drainage.