The Investigation and Evaluation of the Effect of Carbonated Chloride Solution on the Dynamic Interfacial Tension of Acidic Crude Oil

Nowadays, carbonated water injection is one of the effective methods of increasing oil extraction from crude oil reservoirs. In this method, the effect of CO2, temperature, and pressure on dynamic interfacial tension (DIFT) of crude oil/carbonated brine is significant. In this study, using a sample of acidic crude oil with a total acidity of 1.5 g/mgKOH and in the presence of sodium carbonated chloride solution and potassium carbonated chloride solution, the effects of each of the above parameters on DIFT over a wide range of temperatures (30 °C -80 °C) and pressure (500 psi-4000 psi) are examined. Besides, the adsorption time of natural surfactants in crude oil, namely asphaltene and resin on the interface, related to the carbonated aqueous solution/crude oil, was calculated using an experimental descending model (Mono-Exponential Decay). The results included The interfacial tension and adsorption time are compared with the results obtained in the absence of carbon dioxide, i.e., solutions of sodium chloride, potassium chloride, and crude oil. According to the results, with increasing pressure, despite a slight decrease in the equilibrium interfacial tension of crude oil/carbonated brine, little change was observed in the DIFT process. In carbonated solutions, the equilibrium interfacial tension (EIFT) decreases with increasing temperature due to increased molecular motion (increasing entropy). However, in general, it was observed that the presence of CO2 in the aqueous phase increased the EIFT compared to pure brine, which can be attributed to the acidic structure of crude oil and lowering the pH of the aqueous phase as well as reducing the ionization of natural surfactants.