| A three-dimensional, dual-porosity, two-phase mathematical model and numerical model for coalbed methane reservoir were given, according to the theories of coalbed methane geology, reservoir engineering and fluid mechanics in porous medium. And furthermore, a corresponding reservoir simulator has been developed. The major work of this paper includes:(1) By a large amount of surveys on the domestic and foreign literatures, a systematic and intensive study was undertaken. 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) Based on the theory of surface physical chemistry, new theoretical models for the porosity and permeability of fractures in coalbed methane reservoir have been presented in view of the influence of matrix shrinkage.(3) A three-dimensional, dual-porosity, pseudo-steady, non-equilibrium sorption, two-phase mathematical model has been established, and the model includes complex processes of desorption, diffusion and seepage during the exploiting procedure of coalbed methane.(4) Fully implicit numerical solution technique for dual-porosity, two -phase flow mathematical model was given in detail, and a three-dimensional coalbed methane reservoir simulator (CGSim-3D) has been developed by Compaq Visual Fortran 6.6 and Visual C++ 6.0 programming languages.(5) In application to the history matching and production prediction for coal methane production wells in Qinshui Basin, Shanxi province, the reliability and practicability of the simulator are verified. On the basis of the above, an exploitation plan is suggested.
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