Capillary, viscous and gravity forces in gas-assisted gravity drainage

The capillary, viscous and gravity forces were analyzed by performing numerical simulations of gas assisted gravity drainage (GAGD) process. The analysis was conducted using three dimensionless groups: capillary number (the ratio between the viscous and the capillary forces), bond number (the ratio between the gravity and the capillary forces) and gravity number (the ratio between the gravity and the viscous forces). The effect of each number on the oil recovery factor was evaluated. The results that were obtained from the numerical models were also compared with data that were obtained from the physical and visual models, core floods and gravity drainage field projects. The simulation results indicated that before the gas breakthrough, higher oil recoveries were obtained at lower capillary and bond numbers and higher gravity number. In addition, after the gas breakthrough, higher oil recoveries were obtained at higher capillary and bond numbers and lower gravity number. The numerical models are consistent with the reported results in the literature. In conclusion, a numerical simulation with dimensionless groups can be a useful tool to predict the performance of the gas-assisted gravity drainage process. (C) 2014 Elsevier B.V. All rights reserved.