Solution and typical curves of seepage model of water-bearing coal seam with leakage recharge

To study the effects of leaky aquifer on the earlier production of coalbed methane wells, the leaky aquifer model was established based on transient flow theory. The model was solved under Laplace transform, and Stehfest reverse inversion was used to obtain the real space solution, then dimensionless pressure and pressure derivative type curves were created in log-log plots with new parameters. Based on physical flow mechanism, the influence of leaky aquifer on curve shape was concluded that the radial flow would end earlier with stronger leakage coefficient. The way to obtain permeability, skin factor and leakage coefficient by typical curve match was also proposed. Typical curves are useful for evaluating leaky aquifer and guiding subsequent production adjustment of CBM wells.