Activation of Carbonated Brine with Surfactants and Sulfate Anion for Using the Enhanced Oil Recovery Process

Abstract

CO2-based enhanced oil recovery (EOR) methods gained special attention since they can extract trapped oil from depleted reservoirs and store CO₂ in the ground. Respecting these advantages, 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 while pressure is ranged between 0-3000 psi. So, in the first step, the IFT of CO₂ and crude oil is measured to find the first and multiple contact miscibility (FCM and MCM) pressures. After that, two synthetic brines including synthetic sea water (SB) and tuned SB (called SB-2SO₄, i.e. SB spiked with two times of SO₄^2- and depleted from Na+ and Cl-) with the ionic strength of 0.8 M are 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 min][Cl]) and octadecyl-3-methyl imidazolium chloride ([C18 min][Cl]) are 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 pressure intervals of lower, near and higher values of MCM pressure. The best surface activity with very low IFT values and low adsorption time was obtained for C-SB-2SO₄-CTAB, i.e. carbonated solution containing CTAB and tuned brine spiked with sulfate. Finally, the experimental data are used to model the dynamic IFT and calculate the relaxation time.

Keywords: Carbonated brine, Tuned brine, Surfactant, interfacial tension, co2