Preparation and performance of a novel hydrophobic associating polymer with betaine structure as a thickener under high-temperature and high-salinity environments
摘要
High-temperature and high-salinity-resistance polymers are essential as thickeners for enhanced oil recovery in harsh reservoir conditions. However, most synthetic polymers suffer from significant viscosity loss under such extreme environments. In this study, a betaine-type ternary hydrophobic associating polymer (PADA) with salt-induced thickening property was synthesized through the copolymerization of acrylamide, diacetone acrylamide and an amphiphilic hydrophobic monomer. Experiments were conducted to characterize the salt-thickening behavior of this hydrophobic association water-soluble polymers with a betaine structure. Apparent viscosity measurements and fluorescence spectroscopy confirmed the self-assembly of hydrophobic structures in the PADA solution, with a critical association concentration of 0.5 wt%. PADA exhibits excellent salt-induced thickening properties, with divalent ions exhibiting a significantly stronger effect on viscosity enhancement in order of Ca2+ > Mg2+ > Na+. Rheological studies showed that a 0.7 wt% PADA solution exhibited superior temperature stability at 180℃, and shear recovery at 120℃ in a 100 g/L saline solution. Additionally, viscoelasticity improves with increasing salinity, as evidenced by the increase in both storage modulus (G′) and loss modulus (G″) with higher salt concentration. These results suggest that PADA holds great potential as a fracturing thickening agent and enhanced oil recovery polymer for applications in extreme environmental conditions with high salinity and high temperatures.