Preparation and evaluation of thickener for hyperbranched fracturing fluid

Quaternary polymer thickener PHPAE-C was synthesized via radical polymerization of carboxyl terminated hyperbranched macromonomer HPAE-C, which was prepared from diethanolamine (DEA), methyl acrylate (MA), 1,1,1-trimethylolpropane (TMP) and maleic anhydride (MAH), acrylamide (AM), acrylic acid (AA) and 2-acrylamide-2-methylpropanesulfonic acid (AMPS) as monomer in aqueous solution. The structure of PHPAE-C obtained was then characterized with FTIR and 1HNMR, followed by evaluation on its solution properties and crosslinking performance. The results showed that the apparent viscosity of the prepared thickener solution with a mass concentration of 3000 mg/L reached 846.7 mPa•s at a shear rate of 7.34 s-1 and temperature of 25 ℃, still remained at 570 mPa•s as the temperature rose to 90 ℃, and still above 300 mPa•s when the mass concentration of Na+ was 6000 mg/L and those of Ca2+and Mg2+ were 600 mg/L, indicating that PHPAE-C had good viscosity improvement, temperature resistance, salt resistance and shear resistance. Meanwhile, it was found that crosslinking reached best when m(polymer aqueous solution,polymer mass fraction was 0.3%):m(zirconium acetyl acetonate)=100:0.06, crosslinking temperature at 55 ℃ and pH=5. After being continuously sheared at 120 ℃ for 80 min with a shearing rate of 170 s-1, the system showed an apparent viscosity of ~450 mPa•s, exhibiting low damage with good sand suspension and gel breaking performance. © 2022, Editorial Office of FINE CHEMICALS. All right reserved.