The Numerical Simulation of Conventional Ground Coalbed Methane Development

The migration, accumulation, and production of coalbed methane (CBM) are absolutely different from the conventional natural gas. The mechanism of the migration and production of CBM are researched and the geological model of CBM reservoir simulation is presented in this paper. The desorption, diffusion and percolation flow from matrix surface into wellbore are considered. This model introduced the Second Fick Law to consider the absorption and diffusion of CBM, and Darcy Law to consider the percolation flow of CBM. After that, this complex mathematical model is solved by using fully implicit finite difference method. At last, the model is applied for forecasting the gas and water production in the southern Qinshui Basin. The results indicated that the appropriate reduction of well spacing can relatively improve CBM development.