Development and Performance Evaluation of High Temperature Resistant Hydrophobically Bonded Polymer Fracturing Fluids

More and more deep, low permeability and high temperature oil and gas reservoirs have been discovered by exploration, however, there are fewer types of fracturing fluids that can be used for production enhancement and modification of such reservoirs. Due to their high viscoelasticity, water-soluble hydrophobic polymers have been widely used as thickeners of working fluids for drilling and oil repulsion, and have also been applied in fracturing, but their weak temperature resistance limits their applicability to reservoirs, and their high initial viscosity makes them difficult to be formulated in the field. To address the above problems, this paper successfully prepared a high temperature resistant thickener PAAQ based on free radical polymerization method, which is used for fracturing and production enhancement in deep low permeability and high temperature oil and gas reservoirs. The experimental results show that PAAQ has good thickening, temperature resistance, shear resistance, viscoelasticity and other properties, and is suitable for fracture acidizing in carbonate formations.The thickening mechanism of PAAQ is the formation of a three-dimensional network structure by polymer molecular aggregation and chelation of the betaine side chains with calcium ions.The storage modulus G’ of PAAQ solution is always higher than that of energy dissipation modulus G”; k<1.0·10^-3 m/min1/2 , R <1.5·10⁴ m/min, V₀ <5.·10 m^-23/m²; the settling rate of the ceramic particles was lower than 0.48 cm/min; when the NaBO₃ dosage was 0.1%, the viscosity of the fracturing fluid was reduced to 30 mPa∙s at 110 min, which indicated that the fracturing fluid system had good sand-carrying performance, filtration-loss control ability and gel-breaking performance. This paper provides a theoretical basis for the synthesis and application of high-temperature resistant polymer fracturing fluids.