CO2-responsive worm-like micelle(CO2-TWMS)was constructed by mixing CO2-responsive monomer N,N-dimethyl oleic amide propyl tertiary amine(DOAPA)with tertiary amine structure,which was prepared from 3-dimethylaminopropylamine(NNDP)and oleic acid,with anionic surfactant sodium p-toluenesulfonate(SPTS).The responsiveness of the system was characterized by the changes in conductivity,chemical structure and micro-morphology before and after its contact with CO2.The anti-channeling performance as well as the mechanism of the system were analyzed by combining the changes in surface activity,pressure,and recovery efficiency in the process of CO2 displacement in dense matrix/crack medium and CO2-TWMS channeling prevention.The results showed that CO2-TWMS system with n(SPTS)∶n(DOAPA)=1∶1 exhibited the highest viscosity of 4125 mPa·s.CO2 and N2 could stimulate reversible changes in electrical conductivity between 0.90 and 1.95 mS/cm,inducing the micromorphology transformation between wormlike and spherical micelles.In addition,CO2 reduced the critical micelle concentration from 0.63 mmol/L to 0.25 mmol/L,and the lowest surface tension from 30.2 mN/m to 29.1 mN/m.The adsorption efficiency and efficacy of the system at the gas-liquid interface were enhanced,which was conducive to the formation of micelles.In the dense matter-fracture medium,CO2 induced wormlike micelle formation,increased the pressure difference during displacement,expanded the CO2 displacement sweep efficiency,and increased the recovery rate by 22.6％.
关键词
蠕虫状胶束/CO2响应性/致密油藏/防气窜/油田化学品
Key words
wormlike micelles/CO2 responsiveness/tight oil reservoir/anti-gas channeling/oil field chemicals
万方数据