Numerical Simulation Study On Fracturing Technique Of Coalbed Methane Reservoir

Based on the theories and methods of many subjects such as oil-gas geology and mechanics of flow through porous media, the mechanisms of coalbed methane considering starting pressure gradient generation storage, migration and production are studied, also a simplified geologic model of coalbed container rock is established in this paper; then a two-phase, 3-D flow model of dual-porosity media is established when researching on the hydraulic fracturing on the stimulation of coalbed methane; finally, homogenous coalbed methane reservoir trilinear flows finite-conductivity vertical fracture well test model has been established and worked out. Following results have been presented:(1) This study includes the characteristics of coalbed methane reservoir and the mechanisms of the storage, migration and production for coalbed methane, which helps further studies on dynamic exploitation of coalbed methane.(2) A two-phase, 3-D flow model considering the starting pressure gradient of dual-porosity media and coalbed methane was established and worked out. The IMPES numerical method of the mathematical model was given in detail.(3) A three-dimensional, dual-porosity, pseudo-steady, non-equilibrium sorption, two-phase mathematical model has been established, which includes complex processes of desorption, diffusion and seepage during the exploiting procedure of coalbed methane. This model also considers the influence of hydraulic fracturing on the coalbed methane production.(4) Homogenous reservoir trilinear flows finite-conductivity vertical fracture well test model has been established and worked out. Outside boundaries are considered. Effects of wellbore storage, skin and changing wellbore storage are included. Type curves are plotted.