Interfacial dynamics of oil recovery using surfactant floods at nanoscale
Using primary and secondary recovery, only 20-40% of oil can be extracted from an oil reservoir. The remaining 60-80% of oil stays underground where oil is adsorbed on rock surfaces, leading to oil entrapment within the rock pores. At a time of surging global energy demand, researchers are now actively investigating ways to squeeze extra barrels from oilfields via various enhanced oil recovery (EOR) techniques such as gas injection, chemical injection, microbial injection, or thermal recovery. Surfactant flooding, which is one type of EOR, involves the addition of surfactants to water floods to reduce oil-water interfacial tension to ultra-low values so that mobility of oil droplets is increased. The technical feasibility of oil recovery via surfactant flooding were demonstrated in early field tests by various authors. Since then, numerous studies focusing on the bulk oil recovery properties of surfactant floods have been conducted: Majority of these studies have investigated the effects of phase behavior, wettability, interfacial tension, water mobility, and foaming performance on the behavior of oil recovery using surfactant floods. However, while there are a numerous studies on enhanced oil recovery via surfactant floods at the bulk scale, studies on the nanoscale dynamics of oil recovery via surfactant floods are very limited. In this work, we have investigated the kinetics and mechanism of heavy oil recovery using a model non-ionic surfactant solution, 4-nonylphenyl-polyethylene glycol at nanoscale. This study was conducted using four complementary techniques: quartz crystal microbalance with dissipation (QCM-D), atomic force microscopy (AFM), ellipsometry, and dynamics light scattering (DLS).