Study on the Performance of Betaine Surfactant Used in Heavy Oil Production
In order to explore the mechanism and structure-activity relationship of surfactants used in the thermal treatment of heavy oil,the interfacial tension between eight different long-chain alkyl carboxylic acid/sulfonic acid betaine solutions and heavy oil was measured.The effects of temperature,mineralization degree,and divalent ions on interfacial tension were investigated,and the oil displacement performance was studied using microscopic visualization experimental methods.The experimental results show that alkyl chain length.hydrophobic group branching,and hydrophilic group size are the main structural factors affecting the ability of betaine to reduce interfacial tension.Straight chain carboxyl betaine C16BC has the best synergistic effect with offshore heavy oil,which can reduce the interfacial tension between oil and water to the order of 1.0 × 10-4 mN/m.Temperature,salinity,and divalent ions have little effect on the ability of betaine to reduce interfacial tension.During the oil displacement process,C16BC efficiently starts the crude oil through ultra-low interfacial tension,improving the oil washing efficiency.Meanwhile,the water in oil emulsion formed is conducive to migration.Moreover,during the migration process,the emulsion partially coalesces,forming a front end oil wall with a certain viscosity,increasing flow resistance and expanding the coverage range.The oil displacement efficiency of C16BC solution in microfluidic chips has been improved by 24.9％compared to formation water displacement,demonstrating good application prospects.
heavy oilbetaineinterface tensionmicroscopic visualizationoil displacement
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