Offshore CCUS With Carbonated Water Injection

The economic feasibility of applying carbon capture, utilization, and storage (CCUS) offshore is examined by looking at carbonated water injection as an added activity to a standard water injection operation. This added activity requires new equipment and methods, which means additional costs. However, it can also increase oil production and reduce CO₂ tax expenses. Injecting carbonated water has the potential to improve oil recovery by swelling the oil and lowering the interfacial tension between oil and water, allowing it to flow more easily. The efficiency of this process will, in addition to depending on reservoir properties and well placements, depend on concentration of CO₂, salinity, oil properties, temperature, pressure and injection rate. To study the potential effects of carbonated water injection at field scale, reservoir simulations were run using a model inspired by the Norne Field model, initialized with three different types of oil to reflect the range of oil qualities in the North Sea. The economic performance of carbonated water injection was analysed based on the increase in oil recovery and the net amount of CO₂ stored for different oils and combinations of wells. Project costs included CO₂ capture, compression and mixing, upgrading of the well materials to handle carbonated water, as well as a plant to separate CO₂ from the produced gas. Economic assessments were performed for project durations of 20 and 40 years.