Assessment of a surface-active ionic liquid formulation for EOR applications: Experimental and simulation studies

This study aims to assess a surfactant blend for enhanced oil recovery from carbonate rocks. Due to the abundance of these reservoirs, their profitable exploitation would ensure our petrochemical needs are met, and maintain current quality of life. The objective of this work is to increase the technology readiness level of our previous proposal based on the use of a blend of pure sodium dodecylbenzene sulfonate and the surface-active ionic liquid cocosalkylpentaethoximethyl ammonium methylsulfate. To that aim, the method was adapted for its application with a commercially available petrochemical surfactant (RECOLAS103, a mixture of lineal alkyl benzene sulfonates), and reservoir simulations were carried out to evaluate its effectiveness. Phase behavior, stability, dynamic interfacial tension, adsorption and core flooding were the experimental tests carried out. An optimized formulation consisting of 1 wt% of blend (40 wt% RECOLAS103) in synthetic sea water was found stable and able to reduce water-oil interfacial tension down to 0.02 mN/m. The dynamic blend adsorption in carbonate rocks was found to be 0.60 mg/grock, a promising value for the application. Core flooding tests were conducted at 25 and 120 °C and additional oil recoveries achieved ranged from 10.2 to 12.7% of the original oil in place, the lowest production obtained at the highest temperature. This work offers an advance in the application of surfactants for EOR in carbonate reservoirs, since it improves previous proposals that show stability or high adsorption problems. Moreover, a chemical injection optimization was also carried out by simulation with the CMG-STARS software. Results point to the possibility of reaching higher oil recoveries than those obtained experimentally if the extraction method is optimized.