Improved oil recovery using CO2 as an injection medium: a detailed analysis

The main goal of any improved oil recovery (IOR) is to displace the remaining oil in a reservoir; it is achieved by improving the volumetric efficiency and enhancing the oil displacement. Carbon dioxide is considered to have high potential to improve the production efficiency of the reservoir. This process is gaining a lot of relevance these days as one of the best IOR techniques because when CO₂ dissolves in heavy oil, it reduces the oil viscosity, increases the oil swelling, improves the gravity segregation of oil and the internal drive energy. Consequently, this improves the oil recovery from the reservoir. Oil recovery using CO₂ is a win/ win technique because it enhances the oil recovery and can be used as a CO₂ storage option in reservoirs to reduce the greenhouse gas levels in the atmosphere. In the present study, the reservoir simulation is used to predict the reservoir’s behavior using different production scenarios. A reservoir model is constructed using Eclipse and is used to optimize the well. The objective of this study is to enhance understanding of improved oil recovery for a typical reservoir located offshore on Australian continental shelf. The second part of this study focuses on carrying out an economic analysis of the best IOR scenario, with the maximum oil recovery, by analyzing key variables, such as oil prices, capital costs, operation and maintenance costs, CO₂ prices and taxes. The results obtained indicated that proper well optimization performed in high oil saturation areas using sensitivity analysis and optimizing the values of injection and production increases the oil recovery and maximum sweep of the reservoir. The economic analysis carried out on the chosen optimum scenario 4 was found to be very economical with total savings of $173 M.