Solution properties and phase behavior of a combination flooding system consisting of hydrophobically amphoteric polyacrylamide, alkyl polyglycoside and n-alcohol at high salinities†
Application of polymer/surfactant (SP) combination flooding technique is attracting considerable interest in enhanced oil recovery (EOR). In this study, a SP combination system consisting of hydrophobically amphoteric polyacrylamide (HMPAM), C12/14 alkyl polyglycoside (APG1214), and n-alcohol was designed, and its comprehensive performance, including viscosity, oil/water interfacial tension (IFT) and phase behavior was systematically and thoroughly investigated. Four types of dehydrated crude oils with different hydrocarbon component distributions were employed in the experiments. The intermolecular interactions, which were induced by hydrophobic moieties of HMPAM, endowed this unique polymer with favorable thickening efficiency under harsh reservoir conditions. APG1214, prepared from renewable raw materials, reached low IFT within a wide salinity region. In addition, the coadsorption of HMPAM and APG1214 at the crude oil/water interface to form polymer–surfactant complexes, which exhibited higher activity on reducing IFT, and the ultralow IFT were observed with addition of n-alcohol. The variation in zeta potential measurement indicated that HMPAM, APG1214 and n-alcohol cooperatively encircled oil droplets to manipulate the o/w emulsion. Moreover, emulsion phase behavior and particle size distribution analysis confirmed that the rigid cross-link network at the surface of the emulsion, which was constructed synergistically by HMPAM, APG1214 and n-alcohol, stabilized the emulsion phase.