Experimental investigation of N-lauroyl sarcosine and N-lauroyl-L-glutamic acid as green surfactants for enhanced oil recovery application

The vast deployment of surfactants worldwide in various industries has an intense impact on the environment. This led to the quest for surfactants with high performance but less environmental footprint. Therefore, bio-based surfactants derived from renewable sources have evolved as greener alternatives to conventionally deployed surfactants. Amino acid-based surfactants (AAS) prove to be a promising class of biodegradable and biocompatible surfactants with better safety profiles that meet both physiological and ecological requirements. Nevertheless, they are yet to be deployed in enhanced oil recovery (EOR) application due to limited investigation into their EOR potential. Owing to the recent report on the satisfactory performance of sodium cocoyl alaninate in terms of its EOR potential, this current study investigates the EOR potential of N-lauroyl sarcosine (NLS) and lauroyl glutamic acid (LGA). The study encompasses their surface and aggregation behavior, interfacial tension reduction and wettability alteration capability, emulsification, adsorption behaviour and oil displacement test. NLS proved to be more surface-active than LGA due to the additional carboxylate in the head group of LGA. Both surfactants showed high tolerance to salt and hardness, especially at high-temperature conditions. Furthermore, NLS showed superior IFT reduction capability with a minimum IFT of 0.07 mN/m while LGA only attained a minimum IFT of 0.14 mN/m. This results in better emulsifying power of NLS, yet LGA yielded more stable emulsions. In agreement to their high salt tolerance both surfactants exhibited improved performance in IFT reduction at high salinity condition. NLS and LGA also showed good wetting power on the quartz surface, hence altering rock surface wettability. Both surfactants achieved significant oil recovery after waterflooding, with NLS attaining additional oil recovery of 43% and LGA attaining 25%. The optimistic recoveries are due to the low waterflood recovery. NLS and LGA, therefore, prove to be superb alternatives to conventionally deployed EOR surfactants due to satisfactory performances coupled with their environmentally benign nature.