The Potential of Temperature-activated CO2 Production in Situ as an Enhanced Oil Recovery Process

Recent literature has brought up the combination of carbonated water and low salinity water to increase oil recovery from carbonates. In this study, we investigate the effect of bicarbonate on enhanced oil recovery by adding sodium bicarbonate to brine. By changing the temperature to more than 50 °C, the sodium bicarbonate is converted to CO2. Therefore, we can produce CO2 in situ. It is noteworthy to say that at the high pressure found in the reservoir, the analysis from the PHREEQC software shows that CO2 will be dissolved in the brine in low salinities. Several experiments have been conducted to investigate the effect of ionic composition of smart water. Mg2+, Ca2+, and SO42- are among the divalent ions which has a potential effects on the increased oil recovery, while the monovalent ions like Na+, Cl- and K+ does not show any effects. However, in some cases researchers have reported negative effects for the latter types. Among the experiments, there is a lack of experiments investigating the influence of bicarbonate. Dissolved NaHCO3 in the water produces carbon dioxide in-situ in the core plug. This means that injection of corrosive carbonated seawater can be avoided, since carbon dioxide can be produced in-situ.