Comprehensive methodology for chemicals and nano materials screening for heavy oil recovery using microemulsion characterization

This paper reports laboratory scale screening of different chemicals based on microemulsion generation and the feasibility to be recommended for non-thermal heavy oil recovery applications. The objective of this study is to discover optimal chemicals which can form Winsor type 4 oil in water emulsions with heavy oil. The study was performed through visualization of microemulsions generated using vials and microscopic images. The impact of brine salinity on the emulsification was studied thoroughly in order to identify the synergy between the selected chemicals and the heavy oil. An alcohol propoxy sulfate surfactant from the Alfoterra series, Alfoterra S23-7S-90, a non-commercial surfactant blend HORA-W10, performed best for emulsion formation at low salinity conditions (2.5 wt.%, 3.8 wt.%), whereas Polysorbate-type nonionic surfactant Tween 20 performed best for high salinity conditions (6.35 wt.%, 7.6 wt.%). The observed performance was obtained for an oil with a viscosity of 4.812 mPas and 11.74 °API. Moreover, the results helped creating an initial performance correlation, with dependence on two variables: crude oil composition and synthetic brines. Attempts were also made to stabilize oil-in-water emulsions formed with Alfoterra S23-7S-90, HORA-W10, Tween 20 using nanofluids (metal oxides), sodium carbonate, and an anionic polyacrylamide-based polymer (PolyFlood MAX-165). Emulsions were visualized under the Axiostar plus transmitted-light microscope and their stability was studied in order to screen the most optimal chemical (or chemical combinations) available for low cost heavy oil recovery.