Study of a Novel Carboxylic Cellulose Nanofibrils-Ethoxylated Phytosterol-Alcohol Environmentally Friendly System on the Application in Enhanced Oil Recovery

Bio-polymers and bio-surfactants have attracted increasing attention for their application in chemical enhanced oil recovery (EOR) due to the environmental concerns of synthetic chemical agents. Here, a ternary compound system consisted of carboxylic cellulose nanofibrils (CCNF), ethoxylated phytosterol (BPS), and n-pentanol was constructed. The rheological property and interfacial activity of the compound system and the effects of each component at high temperature (80 degrees C) was investigated systematically. The ternary compound system exhibited excellent performance in thickening, IFT reduction (<10(-2) mN m(-1)), emulsification, and better salt tolerance. CBP, the ternary system of CCNF (2000 mg L-1), BPS (2000 mg L-1), and n-pentanol (5000 mg L-1), greatly enhanced the oil recovery (24.3%) in the core flooding tests by its high displacement efficiency and sweep enlargement, which was demonstrated directly in the visual micromodel flooding. As an eco-friendly system with remarkable performance, the compound system of CBP shows great application potential in EOR.