Performance of CO2 flooding in a heterogeneous oil reservoir using autonomous inflow control

CO2-EOR is one of the main methods for enhanced oil recovery. The injection of CO2 does not only improve oil recovery, but also contributes to reduction of greenhouse gas emissions. However, many CO2-EOR project are reporting problems with breakthrough and reproduction of CO2, which results in poor distribution of CO2 in the reservoir. This paper analyzes the world first trial test for the autonomous inflow control valves in a CO2-EOR oil reservoir. The autonomous flow control valves can choke back unwanted fluid such as pure water, gas, carbonized water and pure CO2. Choking back the breakthrough zones, will increase the reservoir area exposed for CO2 and increase the oil recovery. The trial well was originally an open hole well and has been recompleted with inflow control and packers. The packers are installed to isolate the well in three different zones. The autonomous inflow control valves (AICVs) do not require any external connection or force and this makes the valves simple and robust. The valves will locally choke or close in the zones with high water or gas production, and simultaneously produce more from the zones with high oil saturation. The production with autonomous inflow control valves is compared to the historical production data from the open-hole well. Performance curves for oil, water and gas are presented. The trial tests show that the autonomous inflow control valve chokes back unwanted fluid such as pure water, carbonized water and supercritical CO2, and due to this, the drawdown can be increased resulting in increased oil production.