Molecularly designed nonionic hydrophobic association polymers with anti-salt capacity: Enhancing drag reduction at high mineralization levels

The development of advanced anti-salt drag reduction (DR) agents is crucial for enhancing oil recovery rates, particularly in highly mineralized saline water where the network structure of polymers is prone to disruption, resulting in decreased DR. To address this problem, by carefully designing the structure of the hydrophobic association polymer, a new hydrophobic monomer called APO-10 was introduced, which successfully integrated water-soluble groups, and greatly enhanced the polymer's association properties in an aqueous solution. This ingenious approach produced a stable and robust network structure that can effectively resist the harmful effects of salt ions. PAPO-10 was synthesized through free radical polymerization and has hydrophilic EO chains that enhance its water solubility, enabling better extension of the hydrophobic long chain on the tail in solution. This facilitates the association between molecular chains , leading to the formation of a stable network structure even at low concentrations. PAPO-10 demonstrates remarkable properties, including rapid dissolution and exceptional resistance to salt. It delivers a remarkable DR of up to 78.2466 % at a concentration of 500 mg/L, dissolving within a mere 2 min in aqueous solutions. Molecular dynamics simulations confirmed that PAPO-10 exhibits strong polymer chain binding in solution, consistent with experimental results. Overall, this study provides valuable insights into the development of anti-salt polymers in slick fracturing.