流固耦合作用下深部煤层气井群开采数值模拟

针对深部煤层处在较高地应力和孔隙压力环境下，煤层渗透率降低和瓦斯运移表现出非达西渗流及受煤岩体变形耦合作用明显的特点，建立反映深部低渗透煤层特征和瓦斯流动特性的气水两相流流固耦合模型。以耦合模型为基础，通过数值模拟对深部低渗透井群开采煤层气进行较系统地研究，得到不同渗透率和不同井群间距条件下开采煤层气的储层压力、气和水产能大小、压降漏斗、水饱和度、甲烷浓度和井群干扰的变化规律，考虑较高地应力储层变形影响的流固耦合模型的模拟结果比不考虑耦合作用的结果偏小，对于深部煤层气开采必须重视耦合作用对产量造成的不利影响，制定合理的生产制度和布井方案，尽可能保证储层渗透特性受弱化的程度最小。研究成果对深部低渗透煤层气开采有重要意义。

NUMERICAL SIMULATION OF DEEP COAL-BED METHANE MULTI-WELL EXPLOITATION UNDER FLUID-SOLID COUPLING

Aiming at the characteristics of deep coal-bed considerably low permeability and coal-bed methane non-Darcy seepage transport and obvious fluid-solid interaction because of the considerably high porosity pressure and in-situ stress in the deep coal bed methane exploitation, a fluid-solid coupling mathematical model of gas-water two-phase flow with low permeability is established based on characters of deep low permeability coal-bed and properties of methane flow. Deep coal-bed methane multi-well exploitation with low permeability is researched systematically using fluid-solid coupling model by numerical simulation. The change laws of reservoir pressure, gas-water production, pressure drop funnel, water saturation, coal-bed methane concentration and wells interference are obtained under different permeabilities and different well spaces. The numerical simulation results of coupling interaction of higher geostress and coal bed deformation condition are smaller than the results obtained by fluid-solid coupling model with consideration of the influence of reservoir deformation when geostress are smaller than those without consideration of the fluid-solid coupling. The effect of fluid-solid coupling on the output of deep coal-bed methane must be taken into account; and the reasonable production system and well scheme should be established to guarantee minimum damage of the reservoir permeability. The results have important significances for deep coal-bed methane exploitation.