Synthesis and properties of functional polymer for heavy oil viscosity reduction

To address chromatographic separation issues encountered with surfactant-polymer composite systems, a functional polymer (PAA-NA) was synthesized from acrylamide, 2-acrylamido-2-methylpropane sulfonic acid and two functional monomers, namely C14-C22 fatty alcohol polyoxyethylene ether acrylate (AEO15AA) and N-dodecylprop-2-enamide (C12AM), to realize heavy oil emulsification and viscosity reduction under reservoir conditions. Proton nuclear magnetic resonance analysis (1HNMR) verified the synthesis of PAANA. Relevant properties, including thickening performance, salt-tolerance, interfacial activity, and interfacial elasticity as well as heavy oil viscosity reduction capabilities of PAANA, PAA-N comprising C12AM, and PAA-A comprising AEO15AA were studied systematically. PAA-NA exhibited a superior viscosity reduction performance compared to that of PAA-A and PAA-N owing to the synergistic effect of the two functional monomers: (1) the higher the degree of hydrophobic association, the stronger the spatial network structure, resulting in improved thickening performance, interfacial elasticity, and shear resistance. Meanwhile, a tighter interfacial adsorption layer was formed at the oil-water interface, reducing interfacial tension. (2) heavy oil viscosity reduction rates by PAA-NA (87.0%–90.6%) were higher than those achieved with PAA-A (55.7%–76.0%), while PAA-N was unable to reduce the viscosity. The oil-water ratio range that favors the formation of O/W emulsions was wider for PAA-NA (less than 7:3) than for PAA-A (less than 4:6). The synthesis of functional polymer PAA-NA as a viscosity reducer bears theoretical significance for the enhancement of heavy oil recovery