Synergistic Effect of Sodium p-Perfluorononenyloxybenzenesulfonate and Alkanolamide Compounding System Used as Cleanup Additive in Hydraulic Fracturing

Hydraulic fracturing technology is the most important stimulate method to develop unconventional oil and gas resources. The incomplete flowback of the fracturing fluid causes great seepage resistance for hydrocarbon production. Adding cleanup additive composed of surfactant is an effective method to increase the flowback rate, which is more closely related to the oil/water interfacial tension of the cleanup additive. Therefore, the surface tension and interfacial tension of sodium p-perfluorononenyloxybenzenesulfonate and alkanolamide were studied in this work. The compounding system exhibited high interfacial activity, and even the interfacial tension can reach an ultralow state. In addition, the flowback experiments were conducted in tight cores with a permeability of 0.05 x 10(-3)mu m(2), and the flowback rate increased from 42% (interfacial tension of 1.56 mN/m) to 55.17% (interfacial tension of 0.0074 mN/m). Therefore, from the perspective of increasing the flowback rate, the lower interfacial tension of the residual fluid in hydraulic fracturing stimulation should be preferred. Furthermore, the mechanism of the surfactant compounding system to reduce the interfacial tension was revealed by studying the interfacial dilatational rheology (interfacial dilatation modulus), interfacial water molecule content (interfacial free hydroxyl), and interfacial assembly behavior (molecular dynamics simulation). The results provide a reference for the study of oil/water interfacial behavior of surfactant compounding system and provide an alternative cleanup additive for fracturing fluid used in unconventional hydrocarbon production.