Dynamic response of CBM well pressure based on interacting fault boundary

In view that faults have greater effect on the dynamic response of oil/gas well pressure and its derivative, a coalbed methane (CBM) seepage model taking wellbore storage effect and skin effect into account under the condition with infinite outer boundary was established firstly in this paper. In addition, the elementary method for solving this type of model was introduced to get the solution, i.e., similar constructive method. Secondly, the mirror image solution of CBM well at the interacting fault boundary was calculated according to the mirror reflection principle. Thirdly, the analytical solution of CBM well based on the condition of interacting fault boundary was obtained according to the superposition principle. Finally, dimensionless log-log plot, semi-log plot, primary pressure derivative (PPD) plot and second-order log pressure derivative (SLPD) plot of bottom hole pressure were prepared, and the influential laws of interacting fault boundary on the bottom hole pressure of CBM well were analyzed. The conclusions can provide the convenience for logging interpreters and supplement and complete the fault identification methods further.