Study on Phosphorylation Modification of Guar Gum and Its Performance as a Fracturing Fluids Thickener

In order to solve the contradiction between reducing the water‐insoluble content and maintaining high viscosity during the preparation of modified guar gum for oilfield fracturing fluids, sodium phosphate was used as a modifier to prepare phosphoric esterified guar gum in this study. The effects of the reaction conditions were explored by orthogonal and one‐way extrapolation experiments and the optimal process is determined as follows: the reaction temperature is 30 °C, the addition of sodium hydroxide is 1.0% of the mass fraction of guar gum, the addition of sodium phosphate is 0.1% of the mass fraction of guar gum, and the reaction time is 2.0 h. In addition, the temperature stability, fluid properties, and inhibition of clay generation of the phosphorylated products were investigated. The results show that the apparent viscosity of 0.6% guar gum gel is increased by 32%, the water‐insoluble content is 8.98%, and the temperature stability, fluid, and swelling inhibition to clay were improved. The structure of phosphorylated guar gum was characterized and confirmed by Fourier transform infrared (FTIR), DSC, thermogravimetric analysis (TGA), and elemental analysis.