Carbonated Smart Water Injection for Optimized Oil Recovery in Chalk at High Temperature

Injecting carbonated seawater (CSW) slightly enhances oil recovery in chalk reservoirs at high temperatures, making it the most effective brine among tested options. This study, using Stevns Klint outcrop chalk as an analogue for North Sea chalk reservoirs, found that CSW outperformed other brines like formation water (FW), seawater (SW), and carbonated formation water (CFW) in both secondary and tertiary flooding modes. While oil swelling and viscosity reduction were initially hypothesized as key mechanisms, the research suggests wettability alteration is more likely responsible for the observed increase in oil recovery. The study also confirmed CO2 diffusion from the brine to the oil phase but noted that a significant amount of CO2 remained in the brine, with no notable mineral dissolution or changes in pore surface minerals. These findings highlight the potential of carbonated smart water injection as an environmentally friendly method to boost oil production while reducing greenhouse gas emissions.

Islam Khan, M. A., Kleiberg, S. H., Pinerez Torrijos, I. D., Puntervold, T., & Strand, S. (2023). Carbonated Smart Water Injection for Optimized Oil Recovery in Chalk at High Temperature. E3S Web of Conferences, 367, 1008. https://doi.org/10.1051/e3sconf/202336701008