Numerical Simulation Of Carbonated Water Displacement

For the low permeability reservoir,there are some problems such as high water injection pressure,low injection capacity and insufficient.Although CO₂ flooding can make up for the above problems,there are high fluidity and strong gravity segregation in the reservoir.Low spread range and the displacement efficiency is low.Compared with the pure CO₂ injection,WAG can reduce the high fluid ratio of the pure CO₂injection process,but the water lock is produced during the displacement process,and the oil displacement efficiency is low.In order to overcome the water lock and CO₂high flow and gravity segregation,introducting the carbonated water flooding.In order to study the CO₂ diffusion and crude oil expansion during carbonated water flooding,a mathematic model of carbonated water flooding was established to describe the influence of different parameters on CO₂ diffusion and crude oil expansion.The control variable method was used to study the sensitivity of different parameters to equilibrium time between direct contact and indirect contact of carbonated water with crude oil.The parameter sensitivities were in descending order,diffusion coefficient of CO₂ in crude oil,initial carbonated water CO₂ concentration during direct contact;initial CO₂ concentration in carbonated water,diffusion coefficient of CO₂ in water,partition coefficient of CO₂ in oil-water phase and CO₂ diffusion coefficient in oil during indirect contact.Based on the reservoir geology and reservoir physical property in Area N of S Oilfield,the CMG-GEM module is used to simulate carbonated waterflooding.The simulation results are compared with the depletion mining,waterflooding and CO₂flooding.The results show that compared with CO₂ flooding,carbonated waterflood can broaden the reach and yield 10.3%more crude oil than CO₂ flooding.Compared with water flooding,carbonated water can increase flooding efficiency and increase crude oil by 13.7%production,with high value.The effects of different CO₂ concentration and carbonated water injection on the daily oil production and the cumulative oil production were numerically simulated.The injection saturation was 30 m³/m³ and the injection volume was 350 m³/d.