Review of the Application of Natural Surfactants in Enhanced Oil Recovery: State-of-the-Art and Perspectives

Injecting surfactant by means ofchemical enhanced oilrecovery(cEOR) has acquired predominant attention in improving oil recoveryby changing either fluid/rock and/or fluid/fluid interaction due toion-pair forming and/or surfactant adsorption on the rock surface.As the main surfactant role in EOR, IFT reduction refers to adsorbingof surfactant molecules on the residual oil/water interface, whichcauses an increase in capillary number; as a result, trapped oil dropsin porous media get free and start to move through the pore spacetoward the production well. The toxic nature, excessive cost, andenvironmental issues are the obvious limitations in applying the chemicalsurfactants in EOR, hence, looking for a less-expensive and eco-friendlytype of surfactant has become a significant task to researchers tostudy the natural surfactant as an alternative to chemical surfactants.A deep understanding about the classification of natural surfactants,fabrication methods, and the difference between each class is crucialto propose a new plant-derived natural surfactant. This study triedto review up-to-date published studies related to the natural surfactanttypes and prepare a comprehensive catalog respective to natural surfactantthat helps researchers with regard to future work in natural surfactantapplication in EOR. In addition, comparisons of each class performanceand the impact of nanoparticles and the salinity on them in reducingIFT, altering wettability, and improving the recovery factor havebeen investigated. It had been concluded that natural surfactant canbe produced from different plant parts (leaf, root, steam, fruit,and seed) based on the fabrication method. Natural surfactants synthesizedfrom seed oil are stronger, compared with those extracted from theplant part (i.e., IFT reduction by 98%). Generally, injecting naturalsurfactants expressed low to high performance in improving the ultimateoil recovery from 2% to 40% original oil in place (OOIP).

Automated summary

Injecting surfactants through cEOR has attracted significant attention in improving oil recovery by altering fluid/rock and/or fluid/fluid interaction. The reduction in interfacial tension (IFT) by adsorption of surfactants on the oil/water interface plays a crucial role in mobilizing trapped oil in porous media. However, the toxicity, high cost, and environmental issues associated with chemical surfactants have led to the search for natural alternatives. This study provides a comprehensive overview of natural surfactant types and their performance in EOR, including the impact of fabrication methods, nanoparticle addition, and salinity. It was found that natural surfactants synthesized from seed oil showed superior performance compared to those extracted from other plant parts, achieving IFT reduction of up to 98% and improving ultimate oil recovery by 2-40% of the original oil in place (OOIP).