关键词: 清洁压裂液, 蠕虫状胶束, 剪切变稀性, 黏弹性, 性能评价

Abstract: New clean fracturing fluid VES⁃YF was prepared by mixing the betain type amphoteric surfactant YF⁃1 and cosurfactant YF⁃2 with KCl. By measuring the influence of different concentration of YF⁃1, YF⁃2 and KCl on the viscosity of fracturing fluid, the optimized formulation was obtained, which is 2.0%YF⁃1+1.0%YF⁃2+2.0%KCl. The research and evaluation of the system's construction mechanism and its applicable performance were conducted. The results show that VES⁃YF clean fracturing fluid has shear thinning property and good viscoelasticity. The rheological measurement shows that the network structure of worm⁃like micelle exists in the system and can be recovered after shear failure. The apparent viscosity of VES⁃YF clean fracturing fluid is still higher than 80 mPa·s after shearing for 2 h at the temperature of 45 ℃ and the shearing rate of 170 s-1. The system has the advantages of strong sand carrying capacity, good gel breaking property and low core damage rate. VES⁃YF clean fracturing fluid has a broad application prospects in the fracturing operation of low permeability reservoir.

Key words: Clean fracturing fluid, Wormlike micelles, Shear thinning property, Viscoelasticity, Performance evaluation