Nanofluidic Investigation of Surfactant-Assisted Oil Displacement under Nanoscale Confinement

High Resolution Image Download MS PowerPoint Slide Shale reservoirs present major challenges for enhanced oil recovery (EOR) due to extreme nanoscale confinement within their pores. This study demonstrates a nanofluidic experimental platform that enables direct visualization of surfactant-assisted oil displacement in 10 and 100 nm channels. Two nonionic surfactants with distinct molecular structures were evaluated: Surfactant A (12 ethoxylate, 16 methylene) and Surfactant B (18 ethoxylate, 22 methylene). Dynamic light scattering (DLS) revealed micelle diameters of 8.7 and 18.9 nm for Surfactants A and B, respectively. In 10 nm channels, Surfactant A achieved 71.3% oil displacement at 10× CMC, compared to 57.6% for Surfactant B, while both achieved complete recovery in 100 nm channels. The superior performance of the smaller-micelle surfactant highlights the critical role of molecular aggregation and confinement effects in controlling nanoscale transport and interfacial dynamics. These findings establish a direct mechanistic link between micelle size and EOR efficiency, providing new insight into the design of surfactant formulations for oil recovery from ultratight formations.