Wormlike Micelles Properties And Oil Displacement Efficiency Of New-type Salt-tolerant Viscoelastic Surfactants

Partially hydrolyzed polyacrylamide(HPAM)and petroleum sulfonate are widely used as oil displacement agents.However,their insufficient abilities of salt-tolerance impede their industrial applications in high salinity reservoirs.The wormlike micelles formed by zwitterionic surfactants are expected to perform high displacement efficiency in high salinity reservoirs due to its ability to control mobility and reduce the oil/water interfacial tension.Relevant research is mainly focused on wormlike micelles formed by surfactants whose hydrophobic chain is shorter than C18,while seepage behavior and displacement efficiency of surfactants with ultralong hydrophobic chains are rarely studied.Rheological behaviors,interfacial activity,aging stability,seepage behavior and EOR ability of wormlike micelles formed by erucic surfactant EHSB and gemini surfactant VES01 under hypersaline conditions are investigated in this paper,in comparison with HPAM polymer,in order to provide theoretical basis for the practical application of the new-type salt-tolerant wormlike micelles in high salinity reservoirs.The effects of mass concentration,temperature and salinity on the rheological properties of EHSB and VES01 wormlike micelles are studied by advanced rotary rheometer.The increasing of mass concentration promotes the growth and entanglement of wormlike micelles.The differences in rheological properties,salt-tolerance,thermal resistance between wormlike micelles and HPAM are determined.The ability of EHSB and VES01 solutions to reduce the interfacial tension are investigated by using spinning drop interfacial tension meter.Percolation characteristics and oil displacement efficiency of wormlike micelles and HPAM are studied and compared by physical simulation experiments.Obvious differences of movability and adsorption characteristic between wormlike micelles and HPAM are reflected by seepage curves and parameters.The ability of EHSB and VES01 wormlike micelles to enhance oil recovery is superior to HPAM with the same apparent viscosity.Gemini surfactant VES01 considered for field application is not suitable for application in oil fields.The principal of selecting wormlike-micelle oil-displacement systems is established.The wormlike-micelle flooding system should be determined according to the migration characteristic of wormlike micelles,based on the ability of enhancing viscosity and reducing the interfacial tension.