Fluorinated anionic fenugreek gum: their self-assembly behaviors and use as a novel thickening agent in fracturing gel

A novel fluorinated anionic fenugreek gum (FAFG) was obtained with excellent solution, gel, and broken-gel liquid properties in tertiary oil recovery, which were studied in detail and fenugreek gum (FG) and anionic fenugreek gum (AFG) were used as contrast samples. The results show that, compared to the FG and AFG solution properties, FAFG shows self-assembly properties, and inclusion of more fluorinated groups further reduced the critical associating concentration, yielding better associating properties. Compared to the FG and AFG gels, the FAFG gels exhibit good temperature resistance, shear resistance, rheological behaviors, and excellent salt tolerance. These improvements are attributed to the introduction of fluorinated groups and sulfonic groups. Compared to the FG and AFG broken-gel solutions, the FAFG broken-gel solutions presented slightly higher apparent viscosities. Moreover, the FAFG broken-gel solutions had profoundly lower surface tension and interfacial tension and extremely lower formation damage rates. They can hence serve as clean-up additives themselves after gel breaking. This automatically improves the flowback efficiency and reduces the formation damage. The residue rates of the FAFG broken-gel liquids were lower than those of the AFG and FG broken-gel liquids. Combined with its other excellent properties, FAFG would be an ideal component in fracturing gel.