Development And Evaluation Of Ampholytic Surfactant Potentially Used In Tertiary Oil Recovery

Using linear bromalkanes as raw material, ten kinds of homogeneous nonionic-anionic surfactants were obtained through Williamson reaction and sulphating reaction (or sulphonate reaction) in the text. Alkyl tertiary amines were used as initial material to synthesize three kinds of alkyl carboxyethyl trimethylglycine which are anionic- cation surfactants. The structures of nine kinds of sulphate surfactants were identified by IR spectroscopy, ~1H-NMR and elementary analysis and purities were measured by diphase titration. It indicted that the structures of surfactants were accordance with design and the purities were high.Surface tension, brine tolerance, foamability and interfacial tension of nonionic-anionic surfactants were measured. Surface tension measurement exhibits that the CMC of surfactants are rather low and the surfactants have favorable behaviors of lowering surface tension. The ten kinds of synthesized surfactants were found to be salt tolerant within some salinity by measuring brine tolerance. The sodium hexadecyl polyoxypropylene ether sulfate was proved having the highest brine tolerance by comparison.Great predominance was showed for APS12-2 in foamability and stability of foam. 550ml foam was formed and half-life of which was 365s while no NaCl was added. It was found in experiment that volume of formed foam firstly increased sharply then increased slowly even no change occurred as concentration of surfactants increased.The nonionic-anionic surfactants with propylene oxide units showed better effect of decreasing interfacial tension than that with ethylene oxide units, and the effect increased as number of propylene oxide units increased. The effect of decreasing interfacial tension for surfactants having the same hydrophilic groups firstly increased then decreased as the length of alkyl chain increased. It can be deduced that optimum performance would be obtained by adjusting the length of alkyl chain and number of propylene oxide units in molecules of surfactants. Sulphate surfactants and sulphonate surfactants showed similar effect of decreasing interfacial tension within this experiment.