Evaluation of functionalized polymeric surfactants for EOR applications in the Illinois Basin

Molecular modification of water-soluble hydrolyzed polyacrylamide (HPAM) with surfactant-like monomers, known as the functionalized polymeric surfactant (FPS), can be an effective enhanced oil recovery (EOR) method. The FPS–EOR operation is very similar to the conventional polymer flooding (P-Flooding), in terms of the chemical use and field injection costs, but with a potential to further recover more than 5% of OOIP compared to the HPAM–EOR alone. Laboratory tests and a third party core-flood result show FPS can recover more oil than HPAM even at the lower injection pressure. Surfactant-like monomers linked to the FPS backbone improve the microscopic displacement efficiency of water-soluble polymer by pulling them towards the oil–water interface and creating an oil–water emulsion. Unlike the conventional surfactant+polymer (S+P) multi-component systems, single-component FPS–EOR injection has both the sweep efficiency (polymer feature) and the microscopic displacement efficiency (surfactant feature), but can mitigate incompatibility issues such as chromatography separation and surfactant–polymer interactions. Unlike a typical surfactant flooding for which the reduction of oil–water interfacial tension (IFT) to an ultralow level (<10−3 dyne/cm) is required, a typical FPS solution only reduces IFT to a moderate level (∼10−1 dyne/cm) at the polymer concentrations of 1000–3000ppm.