Viscosity-reducing technology for high-viscosity produced fluid in binary combination flooding in Xinjiang Oilfield

In the field chemical flooding test of the Qizhong District of Xinjiang Oilfield, emulsion with high apparentviscosity (4 000 mPa·s) was found in some well, without demulsification and viscosity reduction after placement inseveral days, which affected the oil production and transportation seriously. In order to reduce the apparent viscosity of theemulsion, the effects of demulsifier, heating, ultrasound and salt on the apparent viscosity of the emulsion were studied tosummarize the optimal method for viscosity reduction. According to the study results, quaternary ammonium salt demulsifierhas very poor effect on viscosity reduction of the emulsion. Temperature has a great effect on rheological property ofthe emulsion. With same shear rate, the higher the temperature, the lower the apparent viscosity of the emulsion is. Theultrasound can reduce the apparent viscosity of the emulsion significantly, and the viscosity reduction effect is best in thecondition that the salt content is 10 000 mg/L and the volume ratio of the emulsion and the wastewater is 5:5. Generally, theabove research results are of important guiding significance to the gathering and transportation of chemical flooding highviscosityproduced fluid and its subsequent treatment.