(64a) Determination of CO2 Solubility in Brines of Various Salinities: Application to CO2 EOR and Storage

The release of CO₂, the most dominant greenhouse gas (GHG), into the atmosphere is predominantly a result of excessive fossil fuel use for industrial and transportation purposes. The GHG emissions are responsible for environmental issues such as climate change including an increase in the average global surface temperature. Therefore, a lot of emphasis has been placed on research and development over the past few decades to reduce the amount of CO₂ in the atmosphere through processes such as enhanced oil recovery (EOR) and storage in saline aquifers. CO₂ increases oil recovery through mechanisms such as oil-swelling and mobility control with a fraction of the injected CO₂ permanently trapped in the porous media. Whereas the CO₂ storage in saline aquifers intends permanent storage of the injected CO₂ as a supercritical fluid.

To study the potential of carbonated water flooding (CWF), a subclass of CO₂ EOR, in oil recovery and the potential of solubility trapping, one of the primary storage mechanisms of CO₂ into the saline formations, it is imperative to get an accurate measurement of CO₂ solubility in brines of various concentrations. In this study, we measured the solubility of CO₂ in water and 1, 3 and 5 M NaCl brines under pressure conditions varying from 150 psig to 1200 psig at 65 °F (18 °C) using a simple experimental protocol. The experimental results are compared with a state-of-the-art thermodynamic model for CO₂ solubility. The obtained experimental results are found to be in good agreement with the results obtained through modeling.