A Novel AMD Nanosheet and Surfactant Synergy System to Increase Oil Production under Harsh Reservoir Conditions

Amphiphilic molybdenum disulfide (AMD) nanosheet is a novel flake type nanomaterial for increasing oil production. It shows unique behaviors on oil/water interface as the flake nature compared with particulate nanomaterials. However, nanosheet solution in high salinity water at elevated temperature had poor compatibility, which limited the applications at harsh reservoir conditions. An improved nanosheet system synergetic with a cationic surfactant was developed and showed good compatibility improvement at 95°C and salinity as high as 57,670 mg/L. The interfacial tension (IFT) of the developed nanosheet and surfactant system with crude oil was not ultra-low, but it showed excellent interfacial activities in emulsification tests and phase behavior tests even at low concentrations. Nanosheet produced much stable emulsion than surfactant. Mixing nanosheet and surfactant increased emulsion stability. The hydrophilic and lipophilic balance of the nanosheet and surfactant system could be controlled by surfactant concentration. Winsor III type microemulsion was formed at nanosheet/surfactant concentration ratio of 1:2 to 1:8. For the performance in porous media, the surfactant component reduced the retention of nanosheet and decreased the plugging to the cores. Corelfooding tests in limestone and carbonate cores demonstrated the good incremental oil production performance of the nanosheet and surfactant system at 95 °C. Both oil bank at early stage of nanosheet injection and a long-lasted emulsified oil contributed to the oil production. The oil production performance of nanosheet/surfactant system was affected by both concentration and concentration ratio of the two components. A 50 mg/L nanosheet and 2000 mg/L surfactant formulation showed highest oil production after waterflooding compared with other combinations.