Research On Synthesis And Performance Evaluation Of A Novel Surfactant

A great many of surfactants are needed in EOR。The surfactants developed and applied before were molecules with single hydrophilic group and single hydrophobic chain。The surface activity improvement of surfactant is so limited because of its molecular structure。Since1990s, a new kind of surfactant has been developed。Gemini surfactant has a good many of properties that conventional surfactants do not have, like high surficial (interfacial) activity, low CMC, good salinity resistance, good compatibility with other agents, high-efficient wettability and the unique rheology. Gemini surfactants are raising expectations in EOR. However, some researches found that Gemini surfactants can get ultra interfacial tension only in high salinity water, not in low salinity water. That mainly because Gemini surfactants’hydrophily is so strong that surfactant molecules can not stick to the surface of oil. So it can not reduce the interfacial tension.The main contents of this paper is the synthesis of a novel anionic surfactant with single hydrophilic group and double hydrophobic chains on the basis of molecular structure and it’s properties are evaluated.Anion surfactant sodium diester sulfosuccinate is obtained with maleic anhydride、 alkyl alcohol、hydrogen peroxide、sodium bisulfite as primary material through esterification reaction、epoxidation reaction and additive reaction. Synthesis conditions of each step are discussed through references and experiments, as follows:①Maleic diester, proportion of materials (n(maleic anhydride):n(alkyl alcohol)) is1:2.2; reaction temperature is130℃and reaction time is5h, catalyst is concentrated sulfuric acid. Under this condition, the yield can reach as high as90%.㎎Diester epoxy succinate, proportion of materials (n(Maleic diester):n(hydrogen peroxide)) is1:3; reaction temperature is about10℃and reaction time is8h; Absolute ethyl alcohol is chosen as solvent. Under this condition, the yield can reach as high as85%.③Final product: sodium diester sulfosuccinate, GM-8proportion of materials (n(Diester epoxy succinate):n(sodium bisulfite)) is1:3; reaction temperature is about60℃and reaction time is about5h; Dichloromethane is chosen as solvent. Under this condition, the yield can reach up to80%. Structure of the product of final product is characterized and verified with IR.By using the wilhelmy type method, surface activities of the surfactant are determined. Results showed that①GM-8and GM-10, rather than ordinary single-chain surfactants SDS, has lower surface tension and critical micelle concentration (CMC), lowing one order of magnitude.②Surface tension of GM-8and GM-10gradually reduced as the temperature increased;③Surface tension of GM-8and GM-10gradually reduced as concentration of NaCl and CaCl2increased, meanwhile the addition of CaCl2has more impact on surface tension than NaCl.Interfacial tension between surfactants and crude oil are measured by using TX-500C entire range rotating drop interface tension instrument. Results showed that①Compare with traditional single-chain surfactant SDS, GM-8and GM-10get lower interfacial tension with crude oil.②When solution concentration of GM-8, GM-10gradually increased, corresponding interfacial tension reduced at first and then reached to a stable number, when the concentration added to a certain number.③The oil-water interfacial tension test of0.1%GM-10at45℃and70℃showed that interfacial tension reduced as the temperature rised, the required time to balance was shorter。④The interfacial tension of GM-10with different salinity concentrations has been tested.The results showed that the interfacial tension increased as the concentration of salinity increased, it reached to10-1mN/m when the salinityl concentration was50000mg/L, GM-10showed a good interfacial activity under low salinity condition。⑤The water-oil interfacial tension of combination solution including GM-10and nonionic surfactant OP-10are lower than two separate surfactant’s with the same concentration. The combination solution showed a better interfacial activity.ce ability to high temperature.Experiments of foaming performance showed that①Both GM-8and GM-10have better foaming volume and half foam life period than sodium dodecyl sulfate。②The foam volume and half foam life period increased as the concentration of GM-10increased。③The foam volume of GM-10increased and half foam life period decreased as the temperature increased。④The foam volume and half period of GM-10decreased a little as the concentration of NaCl increased, GM-10showed a certain resistance property to NaCl。⑤Ca2+had a greater impact on GM-10,the foam volume and half period decrease rapidly as the concentration of Ca2+increased。Experiments of emulsifying performance showed that①Both GM-8and GM-10have better emulsifying ability than sodium dodecyl sulfate;②As the solution concentration increasesed, GM-10emulsifying ability gradually enhanced,when concentration reached to a certain number, emulsifying stability index remain stable;③The emulsifying stability decreased as the concentration of salinity increased, GM-10showed a limited salt resistance property;④The combination of GM-10and OP-10showed a better emulsifying property。...