Fast-dissolving twin-tail hydrophobic association polymers drag reducer with salt endurable and shear resistant for slick-water fracturing fluids

Hydrophobic association water-soluble polymers (HAWSP) have been used as drag reducer in slick-water fracturing fluids, however, the shear dilution behavior and poor salt resistance significantly impedes their practical application under complicated working condition. In accordance with the problems, the twin-tail HAWSP P(AM-AA-AMPS-DAPO) was prepared by free radical polymerization in this study. Compared to single-chain and short-chain structures, the twin-tail polymer increased two C12 hydrophobic side chain and hydrophilic EO chain on the basis of AM/AA/AMPS conventional short chain polymer, it was not introduced rigid structures such as rings, which was able to associate more quickly in aqueous solution and the molecular chain stretched faster while ensuring solubility. Under the synergistic effect of twin-tail chain and quaternary ammonium salt cation, P(AM-AA-AMPS-DAPO) was made rapid formation of hydrophobic clusters, and provided a robust network structure, thereby effectively resisting the harmful effects of salt ions and mechanical forces. P(AM-AA-AMPS-DAPO) demonstrated remarkable properties, including rapid dissolution, exceptional resistance to salt and shear resistance. P(AM-AA-AMPS-DAPO) was reached a high drag-reduction rate (DR) 76.05 % at 400 mg/L after shearing 600 s, dissolving in aqueous solution was only 210 s. The tolerance concentrations of P (AM-AA-AMPS-DAPO) to Na + , Mg 2+ and Ca 2+ were respectively as follows: 120,000 mg/L, 8000 mg/L and 8000 mg/L. P(AM-AA-AMPS-DAPO) Molecular dynamics simulations reveal the hydrophobic interaction of P(AM-AA-AMPS-DAPO) in fresh and saline water, and it is analyzed the drag-reduction mechanism.