Investigating the Effects of Carbon Dioxide Injection for Enhanced Oil Recovery - The Brent Group in the Statfjord Field
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According to the Norwegian Petroleum Directorate, the average oil recovery in fields on the Norwegian Continental Shelf is 47\%. Thus, more than half of the reserves are yet to be produced. CO2 injection is a method for increasing the oil recovery. It is efficient mostly due to CO2 characteristics, and the ability to achieve miscibility with residual oil. Favorable changes when miscibility is achieved, is reduction in oil viscosity and interfacial tension, as well as a higher capillary number. In theory, miscible displacement by CO2 can yield 100% oil recovery. However, this is unlikely in a real reservoir due to factors like reservoir heterogeneity, presence of water, injection stream impurities and small scale mixing. Nonetheless, CO2 injection is a proven EOR method with promising results. The Statfjord field is one of the largest fields discovered on the NCS. Production started in 1979, and after several strategies for recovery, the production is planned to stop in 2025. At this point the oil recovery is presumed to reach 68%. Though this is a high recovery compared to global results, there is still a large volume of hydrocarbons left. This imply, an unproduced economical potential. A compositional reservoir model of the Brent Group, in the Statfjord field, was provided by Equinor ASA. The main objective of this project was to develop a recovery strategy starting in 2031. The project proposal is supposed to increase the oil recovery, and the economical potential of the field. The suggested project, imply continuous CO2 injection, from 2031 to 2081.