Chemical flooding with ionic liquid and nonionic surfactant mixture in artificially prepared carbonate cores: A diffusion controlled CFD simulation

Abstract

Improved computational techniques have served as reliable tool in providing accurate reservoir characterisation and also predicting production of oil for a given EOR process. In the present study, COMPUTATIONAL FLUID DYNAMICS (CFD) has been used to simulate surfactant flooding experiments in a 3D geometrical model that replicates an actual artificially prepared calcite powder packed bed (a proxy of carbonate reservoir)) in which core flooding experiments have been carried out. The surfactant slug used in the study is a high salinity aqueous mixture containing surface active ionic liquid (C16mimBr) and a nonionic surfactant (TERGITOL 15-S-9). ANSYS WORKBENCH 15.0 software is used to create the 3D geometry and ANSYS FLUENT 15.0 has been used for solving the governing equations for the system. A mixture model is considered as the multiphase model to study the flow of multiple phases in the porous bed. To take into account the mass transfer of the surfactant into the oil phase as well as the water phase, a species transport model is incorporated in the present simulation.Simulation results were confirmed by the experimental data such that the species transport model coupled with mixture model were found to fit in well to the multiphase flow dynamics. It was found that the mixed surfactants system showed higher efficiency in recovering oil due to minimal fingering effects, ultralow IFT between the surfactant solution and oil and low diffusion rates of surfactant species into residual oil and brine. A delayed water breakthrough time was observed during simulation which attributed to higher oil recovery. Also there was a good match in water breakthrough time for both simulation and experimental surfactant flooding process.