Simulation of Filtration Fields with Different Completion Methods in Carbonate Gas Reservoirs

The Longwangmiao Fm gas reservoirs in the Moxi tectonic structure in Sichuan Basin are characterized by deep burial, high temperature, high pressure, significant thickness, high acidic gas content, and high production rate. The perforating and slotted liner completion modes are usually applied in the area. Based on the filtration flow hypothesis, the gas filtration models of the reservoir near the wellbore have been established by the finite element method. The reservoir filtration pressure field and the gas flow velocity field are simulated, and the influence of perforation on the filtration fields is also analyzed. The simulation results show that the pressure depression cone occurs in both cases of completion mode, meaning that the filtration pressure changes nonlinearly from the supply boundary towards the wellbore. The pressure cone is more obvious in the case of perforation completion than that of the slotted liner completion. The gas flow velocity near the perforation hole is higher than that of the slotted liner opening. Two gas wells with similar physical properties and different completion modes have been selected for test analysis. When the wells are stimulated by the acidizing technique, the testing production of the perforation completion well is higher than that of the slotted liner completion well. The test results are in good accordance with the simulation model results. The filtration models of the near-wellbore area established by the finite element method provide important theoretical criteria and can be used for the selection of the optimal completion type.