Preparation and performance analysis of nano-crosslinking agent for sulphonated guar gum fracturing fluid

In order to solve the problems of poor temperature resistance and low crosslinking efficiency of crosslinking agent for sulphonated guar gum fracturing fluid, in this paper, nano-silica was reacted with 3-aminopropyltriethoxysilane to obtain surface-modified nano-silica, which was then reacted with boric acid and n-butyl titanate to obtain nano-silica-based boron-titanium composite crosslinking agent. Its physical properties and structure were characterized by infrared (IR), laser particle size analysis, X-ray diffraction (XRD), and atomic force microscopy (AFM). The sulphonated hydroxypropyl guar gum fracturing fluids formed by nano-crosslinking agent were analyzed: When the temperature was uniformly increased from 25 to 120°C and the shear rate was 170 s⁻¹, the viscosity was finally constant at about 50 mPa · s, which indicated that the temperature and shear resistance were good; the system had a better filtration-loss reduction performance; the average sedimentation rate of ceramic grains in the fracturing fluid system was 0.00872 cm · min⁻¹, indicating that the system had good sand carrying performance; the damage rate of fracturing fluid filtrate to the core was 23.33%; the gel breaking performance test showed that the fracturing fluid had good gel breaking performance. By analyzing the performance of the fracturing fluid, it can be seen that the nano-crosslinking agent has the advantages of good temperature resistance and high cross-linking efficiency compared with the traditional boron and titanium cross-linking agents.