A Study Of Viscosity Reduction Of Super-Heavy Oil From Binnan By Emulsification

With the continuous exploitation of the conventional crude oil in Shengli oil field, the proportion of heavy oil or super-heavy oil has grown increasingly and the difficulty of the exploitation has also increased year by year. Currently, thermal recovery is the main method of exploitation for heavy oil used in oil field, but by this method the energy consumed in the process is very high, it is not economic and the recovery is also limited. However, the study of emulsifying super-heavy oil into water to form stable O/W emulsion, achieving the goal of viscosity reduction of exploiting heavy oil, was of vital importance.In this paper, the studies were done on the super-heavy oil from Binnan in Shengli Oilfield. The physical and chemical properties of the super-heavy oil were studied. The effect of six kinds of viscosity reducers (sodium hydroxide, sodium carbonate, sodium lauryl sulfate, tenbenzene sulfonate, cetyl trimethyl ammonium bromide, nonylphenol ethylene ether) in reducing the viscosity of super-heavy oil was also investigated. The asphaltene was extracted from super-heavy oil to conduct a study of the correlation of the oil-water interfacial properties (interfacial tension, Zeta potential of the emulsion and interfacial shear rheology) to emulsion stability. The results showed that:(1) Water content of the super-heavy oil was20.4%, the viscosity393.2Pa-s at50℃, the acid number4.33mgKOH/g, the mass fraction of asphaltene and resin separated from super-heavy oil were12.86%and25.77%, respectively. The super-heavy oil was a kind of crude oil of which the viscosity, the acid number and the mass fraction of asphaltene were high. The viscosity of super-heavy oil decreased with the temperature and shear rate increasing, respectively, and it tended to be constant when both of them reached a certain value. Analyzed by IR, SEM and XRD, the results showed that the resin and asphaltene both contained a large number of polar groups, there is a strong interaction between molecules, a large number of micelle formed by the strong interaction between the asphaltene and resin may be the main cause of the super-high viscosity of the crude oil.(2) The six kinds of viscosity reducers all can effectively reduce the viscosity of super-heavy oil. The rate of viscosity reduction reached more than98%at their optimal amount, respectively. However, the super-heavy oil in water emulsions formed by alkali (NaOH and Na2CO3) both were very stable, while the emulsions formed by the four kinds of surface active agents (SDS, SDBS, CTAB and OP-10) all were unstable. The compound viscosity reducer formula determined by the experiment was as follows:the mass fraction of NaOH, SDBS and OP-10was0.06%,0.08%and0.22%, respectively. The rate of viscosity reduction was99.81%.(3) The stability of asphaltene model oil in water emulsion stabilized by SDS, SDBS and OP-10was as follows:the emulsion stabilized by OP-10was the most stable, followed by was SDBS, the emulsion stabilized by SDS was the least stable. Meanwhile, the effect of the three kinds of surface active agents (SDS, SDBS and OP-10), the mass concentration of asphaltene and the salt on the corresponding oil-water interfacial properties (interfacial tension, Zeta potential of the emulsion and interfacial shear rheology) was investigated. The results showed that:in the investigated range, the higher the mass concentration of the asphaltene was, the less stable the corresponding emulsion was, the oil-water interfacial tension increased slightly and the Zeta potential of the emulsion remained about the same; the higher the concentration of the salt was, the more stable the corresponding emulsion was, the oil-water interfacial tension decreased and the absolute values of the zeta, potential of the emulsion decreased. The correlation of the oil-water interfacial properties (interfacial tension, Zeta potential of the emulsion and interfacial shear rheology) to emulsion stability was obtained as follows:the interfacial tension was one of the main factors that affected the stability of asphaltene model oil in water emulsion, the decrease of the interfacial storage modulus G’ and loss modulus G" was conductive to the stability of the emulsion, while the Zeta potential might not play an important role in keeping the stability of the emulsion.