Activation of carbonated brine with surfactants and sulfate anion for enhanced oil recovery processes

Abstract

CO2-based enhanced oil recovery (EOR) methods has gained special attention since they can extract trapped oil from depleted reservoirs and store CO2 in the ground. Considering these advantages, the current study aimed to investigate the effect of CO2 on the performance of both carbonated and activated (solution with tuned ions and surfactants) carbonated brine (CB) on the dynamic interfacial tension (DIFT) of crude oil, under constant temperature of 50 °C and pressure range of 0–3000 psi. In the first step, the IFT of CO2 and crude oil was measured to find the first and multiple contact miscibility (FCM and MCM) pressures. Then, two synthetic brines including synthetic sea water (SB) and tuned SB (called SB-2SO4, i.e. SB spiked with two times of SO42- and depleted from Na+ and Cl-) with the ionic strength of 0.8 M were prepared. Four surfactants including sodium luryl sulphate (SLS, anionic type), hexadecyltrimethyl ammonium bromide (CTAB, cationic type) and two ionic liquids (ILs) namely dodecyl-3-methyl imidazolium chloride ([C12 mim]Cl) and octadecyl-3-methyl imidazolium chloride ([C18 mim]Cl) were selected to examine the effect of surfactant type and alkyl chain length on the IFT concomitant with swelling factor in the presence and absence of CO2 in three different pressures including below, close to and higher than the MCM pressure. The best surface activity with very low IFT values and low adsorption time was obtained with C-SB-2SO4-CTAB, i.e. carbonated solution containing CTAB and tuned brine spiked with sulfate. Finally, the experimental data were used to model the dynamic IFT and to calculate the relaxation time.