| Our country is poor in the conventional crude oil, but is relatively rich in heavy oil, however it brings great difficulty on the exploitation and transportation because of its high viscosity and low fluidity at the low temperature. Now the common heating method applied on the exploitation and pipeline transportation of heavy oil is considered to be high energy consumption, uneconomic and inefficient. Therefore trying to exploit heavy oil source in an economic and efficient way is of great significance to release the contradiction between energy supply and demand, and ensure the security of energy strategy in our country. In this paper, based on the high pour point and low fluidity of waxy heavy oil and waxy crude oil at the low temperature, their fluidities were tried to be improved by emulsifying method. Thus the three dimensional net structure of wax crystals in the waxy heavy oil or waxy crude oil could be prevented by oil/water interfacial membrane due to forming stable waxy oil-in-water emulsion, which would highly improve the fluidity of waxy heavy oil.Dynamic turbidimetric method was proposed to optimize the emulsifier formulas for these oils. The turbidity of diluted sedimentary aqueous phase was measured as a function of stirring time with visible spectrophotometer. The variation of oil volume fraction during the emulsion formation and demulsification processes was characterized with the proposed dynamic turbidimetic method by changing stirring time, the static stability of emulsion was also obtained by changing the standing time during the sampling process, and the experimental error could be reduced by multiple sampling. The influence of mass fraction of NaOH and different emulsifiers on the emulsifying effect of waxy heavy oil emulsion was studied and the results agreed well with those obtained from the phase separation method.The suitable emulsifier formula for waxy heavy oil with the pour point of 47℃and the viscosity of 223.2mPa-s(50℃,Ds=105.1s-1) from Huabei oil field was obtained as follows:the mass concertration of emulsifier mixture(mass ratio of sodium oleate to SDS was 7:3) 0.5%, the mass concertration of sodium triphosphate, NaOH and PAM was respectively 0.15%, 0.05%, and 0.15%. When the mass ratio of oil to water was 6:4 and deionized water was used, by forming stable waxy heavy oil-in-water emulsion with stirring speed and stirring time of 800rpm and 20min, the corresponding pour point and viscosity reduction was respectively 18℃and 86.8%. For another waxy heavy oil H2 from the same oil field, the suitable emulsifier formula was also obtained. When the mass ratio of oil to water was 7:3 and the synthesized mineralized water was used in the experiment, by forming stable waxy heavy oil-in-water emulsions with stirring speed of 250rpm and 600rpm, the corresponding pour point reductions were 20℃and 25℃and the viscosity reductions were 89.79% and 97.46%, while the mass ratio of oil to water was changed from 7:3 to 6:4, the results were better.In addition, a suitable emulsifier formula for waxy crude oil with the pour point of 54℃from Henan oil field were obtained. When the mass ratio of oil to water was 59.5:40.5 and the deionized water was used in the experiment, by forming stable waxy crude oil-in-water emulsions with the stirring speed of 250rpm and 800rpm, the corresponding pour point reduction was respectively 8℃and 17℃and the viscosity reduction was respectively 67.83% and 88.79%.Series of salt resisting amphoteric emuslifiers containing amide group were self synthesized for these oils. The molecular structure was characterized by infrared spectrum and the content was analysed by potentiometric titration. The effects of types of emulsifiers and their molecular structure on the stability of waxy heavy oil-in-water emulsion were examined. Due to the increase of interaction strength with PAM, the emulsion stability was improved significantly by introducing amide group in the synthesized emulsifier. The suitable synthesized emulsifier formula for waxy heavy oil H2 from Huabei oil field was obtained as follows:the mass concertration of emulsifier mixture(mass ratio of oleic acid amidopropyl dimethyl amine oxide to LAO-35 was 7:3) 0.4%, the mass concertration of NaOH and PAM was respectively 0.035% and 0.15%. When the mass ratio of oil to water was 7:3 and the synthesized mineralized water was used in the experiment, by forming stable waxy heavy oil-in-water emulsion with the stirring speed of 250rpm, the corresponding pour point reduction was 20℃, which was equal to that obtained from saled emulsifier formula, and the corresponding viscosity reduction was 96.41%, which was better than that obtained from the saled emulsifier formula. The related mechanism was studied and discussed.The above mentioned results are of significance for the secondary or enhancing recovery and pipleline transportation of heavy oil and waxy crude oil, as well as contribute to recognize the mechanism of fluidity improving for these oils.
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