Nanoscale Dynamics of Heavy Oil Recovery Using Surfactant Floods

The surfactant flooding is one of enhanced oil recovery processes aimed at recovering additional oil after a waterflood. This work investigates the kinetics and nanoscale dynamics of asphalt recovery (heavy oil) via surfactant floods using nanoscale characterization techniques including quartz crystal microbalance with dissipation, atomic force microscopy, ellipsometry, and dynamic light scattering. It was found that while the recovery was inefficient below the CMC, the recovery rate increased with increasing surfactant concentration until a surfactant concentration of 2-3 x CMC, then reached a plateau. Above the CMC, the recovery dynamics could be well described by a two-term exponential decay model, indicating that two different first-order processes are responsible for this behavior. The fast process was found to be related to the formation of larger microemulsions, while the slow process was associated with the formation of loaded micelles. Overall, this article provides new nanoscale insights into the heavy oil recovery using surfactant floods, which may ultimately help researchers to improve the efficiency of oil recovery by surfactant floods.