DETERMINATION OF CO2 SOLUBILITY IN BRINES AND PRODUCED WATERS OF VARIOUS SALINITIES FOR CO2 EOR AND STORAGE

To study the potential of carbonated water flooding (CWF), a subclass of CO₂ EOR, for oil recovery and solubility trapping of CO₂, one of the primary storage mechanisms of CO₂ into the saline formations, it is imperative to have accurate estimations of CO₂ solubility in brines and produced waters of various salinities as a function of pressure and temperature. In this study, we measured the solubility of CO₂ in DI water, two produced water samples obtained from the oil wells located in Oklahoma, and 1, 3 and 5 M NaCl brines as a function of pressure in the range of 150 psig to 1200 psig at 65 °F (18 °C) using an in-house experimental method. The solubility of CO₂ was found to have a strong exponential relationship with the density of aqueous brines and produced waters. The experimental results are found to be in good agreement with that of the data predicted using a state-of-the-art thermodynamic model for CO₂ solubility in aqueous brines.