Effect of roof aquifers on the coalbed methane well pattern productivity

According to the rock mechanical properties and the constitutive relation of coal poroelastic mediums,a new cleat permeability model with coal matrix shrinkage effects was derived.On the basis,a three-dimensional network of coalbed methane vertical wells to be nonequilibrium sorption under the conditions of gas-water two-phase flow mathematical model was presented.A coalbed methane reservoir simulator was developed,and the numerical simulation forecast of five-spot pattern was done by the data of given block in the Southern Qinshui Basin.The results indicate that the limestone bed in Carboniferous system with strong water yield property may cause unfavorable influence on the coalbed methane exploitation in the development practice,especially in the fracturing stimulation process.Furthermore,the matrix shrinkage effect on the fracture permeability is also indispensable.