Study On Injected Steam-assisted Self-emulsifying System For Reducing Viscosity Of Super-heavy Oil

In this paper,I introduce the classification of heavy oil and various factors affecting themobility of heavy oil, analysis and compare the various mining methods of heavy oil, it cameto a conclusion that viscosity reduction by emulsifying was widely used and the process issimple, as well as economical，it is one of the most potential and promising methods forviscosity reduction. At the same time, in this paper we discusse the present situation at homeand abroad and the mechanism of viscosity reduction by emulsifying. Due to the viscosity ofsuper-heavy oil is high,and it could not be stirred at low temperatures. Thus the thought ofviscosity reduction by emulsifying is put forward.In this paper, the thought of self-emulsifying drug release system is used for reference,the best formula of self-emulsifying system was optimized by experiments and the stability ofthe emulsion was evaluated. Oil/water ratio on the viscosity of heavy oil, salinity effect on theviscosity and influence of the self-emulsifying system on the interfacial tension of theemulsion were studied. The effects of steam injection, self-emulsifying and steam-assistedself-emulsifying were compared. Finally we came to the conclusion that steam-assistedself-emulsifying is more stable and has better effects in viscosity reduction.The results show that the best formula of self-emulsifying system is0.5%Na2CO3+0.6%APS+0.6%T8+0.9%DP,which can make the viscosity reduction rate of super-heavy oilover95%. With the increase of the surfactant mass concentration, the effect of viscosityreduction got better. But when the surfactant mass concentration reaches a certain degree, theviscosity emulsion basically remain constant. With the Oil/water ratio rises, the emulsionviscosity becomes higher. When the temperature gets higher, the stability gets worse. Besidesplacing the emulsion at high temperatures is not conducive to the stability of the emulsion.The higher salinity is, the worse of viscosity reduction is. The self-emulsifying system cangreatly reduce the oil-water interfacial tension of the emulsion and it is conducive to theformation of emulsion and emulsion stability. Steam injection has a low viscosity reductionrate but the stability is good. Self-emulsifying has a high viscosity reduction rate but thestability is bad. Injected steam-assisted self-emulsifying system has a high viscosity reduction rate，which can reach97%, and the stability is good, the viscosity can keep under500mPa·swhen placing the emulsion for12h at80℃.In a conclusion, it can be used in heavy oilexploitation to improve the recovery efficiency.