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.