Alkyl Ether Carboxylate Surfactants for Chemically Enhanced Oil Recovery in Harsh Field Conditions

Abstract

Abstract Chemically enhanced oil recovery (CEOR) technologies are among the most attractive EOR methods because of the significant amount of incremental oil could be produced by their use. A challenge is that often the chemicals cannot be applied in demanding reservoirs with high salinities and high temperatures due to their limited stability. Our objective is to introduce a novel alkyl ether carboxylate (AEC) based surfactant which exhibits both an outstanding tolerance against high temperatures and high salt concentrations, while delivering high interfacial activity. The solubility and the interfacial properties of the surfactant alone as well as its formulations are investigated under harsh conditions; the performance is determined by characterizing the interfacial properties through spinning drop measurements and phase behavior studies. Chemical stability of the surfactant is also probed by storing a solution at high temperatures; conservation of the chemical structure is followed by analytical testing with HPLC. The chemical stability of the surfactant has been investigated and demonstrated. Ultra low interfacial tensions between crude oil and saline water (up to 140,000 ppm total dissolved salt including 5,000 ppm hardness ions) were observed at surfactant concentrations of about 2,000 ppm at temperatures of 60°C and far above. A novel alkyl ether carboxylate (AEC) with outstanding performance under harsh conditions, e.g. high salinity, is presented as an alternative for unlocking the possibility of chemical EOR for challenging reservoirs.