Modeling and simulation of coupling enhanced Oil/Gas recovery with CO2 injection

Abstract

The present thesis aims to study enhanced oil recovery with CO2 injection (EOR-CO2). In order to study CO2 injection at pore-scale, an isothermal Lattice Boltzmann Model (LBM) with two distribution functions is adopted to simulate density-driven natural convection in porous media with irregular geometry obtained by image treatment. The present analysis showed that after the onset of natural convection instability, the brine with a high CO2concentration infringed into the underlying unaffected brine,in favourof the migration of CO2 into the pores structure. With low Rayleigh numbers, the instantaneous mass flux and total dissolved CO2 mass are very close to that derived from penetration theory (diffusion only), but the fluxes are significantly enhanced with high Ra number. The simulated results show that as the time increases, some chaotic and recirculation zones in the flow appear obviously, which promotes the renewal of interfacial liquid, and hence enhances dissolution of CO2 into brine. This study is focused on the scale of a few pores,but shows implications in enhanced oil/gas recovery with CO2 sequestration in aquifers. An isothermal lattice Boltzmann model for the natural convection in a VAPEX boundary layer is developed. A comprehensive parametric study of natural convection in CO2-oil contact region is carried out for various values of oil viscosity, permeability and inclination angle. We found that the flow structures together with the mass transfer mechanism are significantly dependent on all these parameters.The analysisof thermal effect on the dissolution of carbon dioxide through natural convection at the boundary layer of solvent chamber of CO2-VAPEX showed that it has negative consequences on this process