Study On Synthesis And Properties Of Non-polyether Demulsifiers For Heavy Oil At Low Temperature

In this paper, based on the drawbacks of demulsification difficulty, highly temperature ofdemulsification and so on for heavy crude oil of Liaohe Oilfield, a series of differentproportion of hydrophilic, hydrophobic groups of non-polyether emulsion breaker for heavycrude oil at low temperature, which were prepared with methyl methacrylate, butyl acrylate,methacrylic acid, acrylic acid as raw materials. Mainly studied its demulsificationperformance and mechanism of action, main influencing factors of demulsification difficultyfor heavy crude oil have been studied, and explore the relationship between interfacial filmstrength and demulsification performance.Eight kinds of LG series of non-polyether demulsifiers were synthetized by experiment,in the high temperature of85℃, adding120ppm dosage of demulsifier, selected the effect ofthree kinds of emulsion breakers is relatively good, they are n(-COO-): n (-COOH)=3:1(LG3),4:1(LG4),5:1(LG5), and the best is LG4, but there is still a gap compared tothe polyether demulsifier LP. Study the demulsification effect of mixing LG3、LG4、LG5andLP according to different volume ratio, and compared with single dose, it is obtained thatwhen LG4and LP are compounded by V(LG4):V(LP)=1:1, the dewatering rate is the highestand up to93.33%, the water is the lowest for5.65%in the dehydrated crude oil.We measured the surface activity and interfacial activity of demulsifier, found that thesurface activity and interfacial activity can not directly react good or bad of demulsificationeffect, but due to the wetting and infiltration, the larger the surface activity and the interfacialactivity are, the more easily adsorbed to the interface demulsifier molecule is, to reduce theintensity of interfacial film.Then LG4、LP、V(LG4):V(LP)=1:1complex are investigated for the low temperatureperformance, in the low temperature of80℃, adding120ppm dosage of demulsifier, thedemulsification effect is obviously poorer than85℃, but the best is still V(LG4):V(LP)=1:1composite emulsion breaker, the water is the lowest for7.84%in the dehydrated crude oil. At80℃, it is found that improve dosage of the demulsifier has a certain promoting effect on thedemulsification, but the range is not remarkable.In the breaking process, interfacial film strength is an important factor affecting thestability of emulsions. In this paper, using single droplet rupture rate of LG4、LP、V(LG4):V(LP)=1:1compound demulsifiers to measure the interfacial film strength, toexplore the relationship between interfacial film strength and demulsification performance.The study found, there is a direct relationship between interfacial film strength and demulsification effect, the demulsification effect depends largely on the change of interfacialfilm strength, the stronger the ability of demulsifier to reduce the intensity of interfacial film,the better the demulsification effect; demulsifier and temperature are the important factorsthat affect the intensity of interfacial film, the two directly reflect the demulsification effect,the same demulsifier, the higher the temperature, the stronger the ability of reducing theintensity of interfacial film. The experiments show that V(LG4):V(LP)=1:1compositeemulsion breaker has the strongest ability to reduce the interfacial film strength.