A Simulation Study of Steamflood Process with Co-Injection of Steam-Carbon Dioxide for Oil Recovery

Abstract

Steamflood as one of thermal EOR method is effective to reduce the amount of oil left in the reservoir by mechanisms such as reducing the viscosity of the oil, oil evaporation, and displacement by steam. In this method, fluid is injected continuously into some injection wells to displace oil and obtain production from other wells. However, there are problems with steamflood process that are still not optimally solved. There is an early channelling of steam under the cap rock to the production well which leads to investigating a solution by co-injecting gases to steamflooding processes. Carbon dioxide is co-injected with steam to form gas-drive so it is expected to be able to add sweep in reservoir and also increase oil in place as gas dissolves in oil. Thermal simulation was carried out in this study using CMG STARS reservoir simulator by constructing two kind of injection schemes; steamflood only and steam-CO2 to study the performance of each method. The analysis in this research investigates the effects of steam-gas simultaneous injection in a heavy-oil recovery process specifically to the microscopic and macroscopic efficiencies. The sensitivity of some parameters in the simulation including injection rate, steam quality and slug size of gases injected are also evaluated. The result of simulation shows the highest efficiency from field-scale model is obtained from steam-CO2 method. From sensitivity analysis, it is shown that the increase of injection rate and steam quality of gas injected gives the higher recovery, but the oil recovery decreases as the slug size of gas increasing.