Three-phase flow WAG processes in mixed-wet porous media: Pore-scale network simulations and comparison with water-wet micromodel experiments

The pore-scale physics of water-alternating-gas (WAG) injection is still not completely understood. We summarize the development of a 3D pore-scale network simulator for capillary-dominated three-phase flow in media where wettability varies from pore to pore. Reduction of phase continuity has required incorporation of multiple displacements for mobilization of disconnected phase clusters. WAG processes have been simulated, for which saturation paths are recorded along with statistics of phase pore occupancies and displacement mechanisms, showing the importance of multiple displacements. Furthermore, using 2D network simulations, we have modeled the WAG floods following primary drainage and initial waterflooding in a water-wet micromodel. Good qualitative agreement is found, in particular with respect to the displacement mechanisms occurring during the WAG cycles.