Simulation research on Jamin effect and oil displacement mechanism of CO2 foam under microscale

Abstract

CO2 foam can solve the problems of serious water invasion in the later stage of water injection development of conventional reservoirs, fracture channeling in unconventional reservoirs and low production rate of medium and low permeability reservoirs caused by reservoir heterogeneity, and the Jamin effect is the key to its role. In order to investigate the influence of injection rate, liquid phase viscosity, surface tension, pore structure on the resistance of CO2 foam through the pore throat and the influence of CO2 foam Jamin effect on enhancing oil recovery, the micro-scale pore throat models were established, and the interface changes were traced by using the level set and phase field methods. The results show that the greater the injection rate or liquid phase viscosity, the greater the pressure and the foam film strength, the greater the Jamin effect resistance; Jamin effect resistance is positively related to surface tension, the greater the surface tension, the greater the driving force required for difficult deformation; Jamin effect resistance is negatively related to radius of pore throat, the greater the radius of pore throat (the smaller the pore-throat ratio), the smaller the Jamin effect resistance; CO2 foam plays an important role in the oil displacement, and it can displace the oil trapped on the wall, and the oil recovery of CO2 foam flooding is 9% higher than that of water flooding. The smaller the oil–water interfacial tension is, the more CO2 foam displacement is. These research results have certain theoretical significance for the effective use of CO2 foam in oilfield development.