Polyetheramine enhanced biosurfactant/biopolymer flooding for enhanced oil recovery

The application of conventional alkali, surfactant and polymer in alkali/surfactant/polymer (ASP) flooding has exposed the inherent shortcomings of pollution and damage to reservoirs. Hence, finding new environmentally friendly alternatives is essential for the sustainable development of ASP flooding. In this paper, we proposed a novel ternary combination utilizing organic alkali polyetheramine, biosurfactant, and biopolymer as alternative chemical agents for ASP flooding. Specifically, the ASP system composed of polyetheramine D230, biosurfactant sophorolipid (SL) and biopolymer welan gum (WLG) exhibited excellent potential in improving oil recovery. The interfacial tension measurements proved that D230 could react with organic acids in crude oil to generate surface-active soaps, which cooperated with SL to reduce the oil–water interfacial tension to 10⁻² mN/m. The rheological measurements demonstrated that the addition of D230 could increase the viscosity of low concentration WLG solution, but this phenomenon gradually disappeared with the rise of WLG concentration. Even at higher WLG concentration, D230 only caused a slight decrease in system viscosity, which facilitated the improvement of sweep efficiency. Emulsification and contact angle measurements indicated that D230/SL blend had outstanding emulsifying ability and successfully altered the quartz surface from oil-wet to water-wet. Core flooding experiments and micromodel experiments showed that the D230/SL/WLG system significantly enhanced oil recovery by 22.66 %, which was attributed to the high viscosity, low interfacial tension, excellent wettability reversal and emulsifying abilities of the system. The economic benefit assessment indicated that this ASP system has the potential to be economic, rendering it profitable even during periods of low oil prices. Furthermore, the EC₅₀ value of 52,600 mg/L for D230/SL/WLG demonstrated its environmental friendliness.