| Surfactants are widely applied in the oil field. Along with the exploitation of oil and gas fields, surfactant needs to be good heat-resistant and salt resistance. Fluorocarbon surfactant is one of the most important surfactants which has the highest surface activity,good heat-resistant and salt resistance. Perfluorooctane carboxylic acid and diethanolamine are used to synthesize perfluorooctane carboxylic diethanolamide(FCDA) in this paper. The influence of reaction conditions on the yield are investigated and optimum experimental conditions were found. Also structure of the product characterized by IR spectra. Then the surface activity of FCDA is studied. The results show that the surface tension of surfactants was 19.07mN/m and CMC is 0.012mol/L. The influence of temperature and salt on the surface tension are aslo discussed. The FCDA still displays good foam characters when have the high content of oil and solt. The absorption isothermal curve of FCDA on the sandstone displied as the Langmuir's type and the absorption capacity is 18.9μmol/g. Further more ,the surface activity and foam characters of mixture of FCDA with anionic hydrocarbon surfactants,and nonionic hydrocarbon surfactant in different ratio are also investigated. The influence of the mixed system such as the type of surfactant, concentration, inorganic salt and so on are discussed in this paper.All the results show that FCDA have many good characters, such as high surface ability, the low CMC, high heat resistant and salt tolerance. And finally, core displacement experiment shows that the oil recovery could be increased 21.4% on the foundation of water-displacing.
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