Investigation into the role of microbially produced biosurfactants in enhanced oil recovery

Abstract

Crude oil remains a major global energy source, but its extraction is often limited by various constraints, including low reservoir permeability, high oil viscosity, and high interfacial tension between oil and water. To overcome these limitations, Microbial Enhanced Oil Recovery (MEOR) methods present a modern, promising, and environmentally friendly alternative to traditional chemical agents. In this work, the efficiency of a produced biosurfactant was evaluated by measuring its emulsifying capacity (E24 and E48 indices) and by investigating the influence of physicochemical parameters, specifically pH and salinity, on emulsion stability. The experimental results clearly demonstrate that these factors play a decisive role; a neutral pH (pH=7) provided the best emulsifying capacity, yielding stable emulsions at 24 and 48 hours, whereas strongly acidic (pH=4) or basic (pH=11) environments completely inhibited surfactant activity and prevented emulsion formation. Furthermore, among the tested salinity concentrations (0.03 g/mL, 0.05 g/mL, and 0.1 g/mL), the intermediate value of 0.05 g/mL yielded the highest E24 and E48 indices, while a slight decrease in activity was observed at 0.1 g/mL, indicating that excessively high salinity adversely affects the interactions between the oil and aqueous phases. In conclusion, this study highlights that biosurfactant efficiency highly depends on the optimization of environmental conditions— specifically a neutral pH and moderate salinity—and confirms its significant potential as a sustainable and high-performance alternative for the oil industry