The paper presents a discussion to identify the most applicable method to analyze the pressure transient tests in coalbed methane reservoirs. The assumptions and data requirements for the Perrine-Martin method and the pseudopressure method along with their applicability in coalbed methane reservoirs were discussed. The results of the analytical methods were compared with the results obtained from the a finite difference simulator. To validate the methods chosen for estimating the permeability in a coalbed methane reservoir, actual field data were used. The permeability values from the simulator were compared to the analytical solution methods. It was observed that analytical methods do not give accurate estimates for the field examples. By oversimplifying or neglecting desorption of methane in the analytical methods, inaccurate estimates of permeability were obtained. Thus, the chosen method for analysis of transient and longer term production data is to use a coalbed methane simulator which includes diffusion and desorption.
Proceedings - SPE Annual Technical Conference and Exhibition