| With increasing difficulty of Chinese oil and gas production,application of surfactants in the oil and gas development has been received more and more attention,for exemple,foaming drilling,discharging water and producing gas in natural gas production well and surfactant oil displacement.In this paper,three series surfactants were synthesized.Some abilities were evaluated,including surface and interface tension,foaming ability and emulsification ability.On these basis,foam micro structure changes over time as well as emulsion microstructure of synthetic surfactants were observed by microscopy which Reveals the different foam decay mechanism of surfactants and the relationship between structure and stability of emulsions.All contents of this paper are summarized as follows:(1)A series of surfactants name B1-B4 were synthesized with sodium dodecyl benzene sulfonate(B0)and formaldehyde as reactants.They can reduce the water-oil interface tension effectively in the experiment temperature range,for example,B3,the best in this series of surfactant,can reduce the oil-water interfacial tension from 0.7 mN/m to 0.1 mN/m.The best foaming concentration of B0-B4 are also 0.7% and temperature have a greater influence on the foaming ability of B0.The declining mechanism of all foam is flowing back.All emulsion particles are spherical and emulsion particles have great influence on the stability of emulsion: particles larger,poorer stability.After a period of time,foam shapes of B0 changed into polygon from spherical while B1-B4 also spherical.Emulsion would be layered over time,which was crude oil,emulsion and water from the top to bottom.(2)A series of surfactants name K1-K4 were synthesized with sodium dodecyl sulfate(K0)and formaldehyde as reactants.The best foaming concentration of K0-K4 are also 0.4%.Temperature,methanol & inorganic salts have a greater influence on the foaming ability of B1-B4 and the declining mechanism of their foam is flowing back while B0 is gas diffusion.In the presence of methanol and inorganic salts,foam will accelerate disappears but when the methanol concentration is lower than 20%,foam of K1-K4 can stable for a long time.When the salinity reaches 200g/L,K4 still produce 350 mL foam,which shows some resistance to salts.After a period of time,foam shapes of K0,K1,K3 and K4 changed into polygon from spherical while K2 also spherical.Emulsion would be layered over time,which was crude oil,emulsion and water from the top to bottom.Synthetic products have a great foaming ability and resistance to high temperature,methanol and salts,in the petroleum and petrochemical industry can be used in gas wells drainage operation.(3)A series of surfactants name Y1-Y4 were synthesized with sodium oleate(Y0)and formaldehyde as reactants.They can reduce the water-oil interface tension effectively at different temperatures.At the concentration of 1.0%,Y1-Y4 can significantly the oil-water interfacial tension.At 0.5%,Y1 reduce the oil-water interfacial tension to 0.001 mN/m;at 1.0%,the oil-water interfacial tension shall be reduced to 0.0001 mN/m in 30?,and when the temperature rise to 60 ?still reduced to 0.002 mN/m.The best foaming concentration of Y0-Y4 are also 0.4% and temperature have a little influence on the foaming ability.All emulsion particles are spherical and emulsion particles have great influence on the stability of emulsion: particles larger,poorer stability.After a period of time,foam shapes of Y3 and Y4 change into polygon from spherical while anthers also spherical.Emulsion would be layered over time,which was crude oil,emulsion and water from the top to bottom.Synthetic products have a great role in reducing water-oil interface tension,in the petroleum and petrochemical industry can be used in oil producing operation extraction work. |
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