Biosurfactant Derived from Fenugreek Seeds and Its Impact on Wettability Alteration, Oil Recovery, and Effluent Treatment of a Rock System of Mixed Composition

Surfactant flooding is a method practiced for chemically enhanced oil recovery (EOR) to pursue oil displacement efficiency by lowering the interfacial tension and changing the wettability. However, the application of natural surfactants in oil recovery is an effective way to reduce surfactant adsorption in porous media. Thus, this study gives insight into saponin derived from fenugreek seed as a natural surfactant and utilized for oil recovery into different porous and permeable rock matrixes that consist of sandstone, carbonate, and their conjugates in varying concentrations. The natural surfactant was found to be effective at low concentrations based on its interfacial tension (IFT) value (10 mN/m at CMC 0.2 wt %). The natural surfactant solution profile exhibited shear-thinning behavior at ambient and high temperature conditions. The results of ultraviolet–visible (UV–vis) absorbance from the findings also reveal reduced adsorption on the carbonate surface and proven potential to affect the rock wettability during oil recovery. However, 58% of OOIP oil recovery was achieved in sandstone, which was higher than the recovery in carbonate rock (50% of OOIP) and conjugate rock systems (57% of OOIP). In line with this study, a novel mechanism for the treatment of effluent produced during oil recovery was found. The mechanism for effluent treatment is a combination of gravity segregation and heat treatment. Additionally, the heat treatment mechanism for effluent treatment was found to be one of the effective techniques in this study, and a maximum oil recovery of 4.2 (sandstone), 3.4 (carbonate), and 3.9 (conjugate rock) % OOIP was achieved. The findings of this study thus conclude an important outlook for surfactant flooding using natural surfactant derived from agro-products like fenugreek and highlights the potential of natural, economical, and eco-friendly surfactants.