Preparation and viscoelasticity of a novel hydrophobic associating polymer with salt stimulation responsiveness by functional monomer modification for fracturing fuids

Abstract

Abstract In this study, a salt-resistant hydrophobic association polymer (PZDY) is synthesized by acrylamide, octadecyl dimethylallyl ammonium chloride and decane polyoxyethylene ether acrylate by aqueous polymerization. The infrared spectroscopy, fluorescence spectroscopy, scanning electron microscopy and other characterization methods were used to study its properties, and the rheological properties of PZDY solution is analyzed. The results showed that when concentration of NaCl is less than 5 wt% and CaCl2 is less than 1 wt%, the viscosity of 0.4 wt% PZDY increases with the increase of salt concentration. When the salt concentration continued to increase, the PZDY viscosity gradually decreased. Investigation of the rheological behavior showed that 0.6 wt% PZDY in 5 wt% NaCl and 1 wt% CaCl2 solution, could withstand a temperature up to 180 °C, after being sheared for 2500 s at 170 s−1, and its viscosity was greater than 50 mPa·s. Moreover, the viscosity of 0.6 wt% PZDY in 5 wt% NaCl increased from 104 to 205 mPa·s and the viscosity of 0.6 wt% PZDY in 1 wt% CaCl2 increased from 110 to 157 mPa·s, when at a shear rate of 170 s-1, at 180 ° C and the shear time was less than 500 s. Meanwhile, SEM results showed that salt addition enhanced the quasi-spatial network structure, with closer clustering of PZDY molecules in NaCl solution than in CaCl2 solution. The storage modulus (G′) and loss modulus (G") increased with the increase of PZDY concentration. Therefore, PZDY can be used to improve the heat and shear resistance of fracturing fluids and enhance oil recovery.