| Phase inversion was a particular phenomenon to distinguish the oil-water dispersion flow from other flow patterns. The rheological characteristics of the dispersion and associated pressure drop change abruptly and significantly near the phase inversion point, which exerted adverse impact to pipeline operation. Accordingly this thesis studied the phase inversion phenomenon from two aspects: 1) direct experiments whereby white oil and water were injected simultaneously into the pipe at a certain concentration; 2) continuous experiments during which the dispersed phase was injected into pipe and its proportion gradually increased, including oil to water and water to oil experiments. By changing the oil products and altering the mixture velocities and temperature, this paper summarized the effects these factors induced to direct experiments and continuous experiments.The results showed: In the direct experiments, the phase inversion point had a declined tendency as flow rate of the mixture increase, ultimately reached a constant value; The phase inversion point increased with the increase of oil viscosity; The phase inversion point of the mixture with high viscous oil exhibited a growing tendency as the temperature increased. In the continuous experiments, the ambivalent region limits of lower viscous oil mixed with water had a wider tendency as flow rate of the mixture increase, in the case of other oil, it did not have the regularity; The ambivalent region limits decreased with the increase of oil viscosity; Temperature on the impact of ambivalent region did not have obvious regularity.Combined wih the high speed photography system and isokinetic sampler system, studied on the phase inversion process came to a conclusion: In the water to oil experiments, oil droplets of pre-phase inversion showed unregularity, the water droplets of post-phase inversion turned into spheres, and secondary dispersion appeared; In the oil to water experiments, secondary dispersion did not appear pre- and post-phase inversion. Phase inversion did not happen simultaneously throughout the pipe, factually, it happened gradually as the fluid flowed through the pipe. The wettability of the pipe also affected the pressure drop of the pipe.Compared the experimental datas with the predicted values of viscosity models, it was found that the experimental datas were in accord with the Brinkman&Roscoe model and Furuse model closely. According to a model for slug liquid holdup is developed based on a balance between the turbulent kinetic energy of the liquid phase and the surface free energy of dispersed gas bubbles by Zhang, this paper ignored the turbulent kinetic energy caused by energy transfer between continuous phase and dispersed phase, referred to Furuse model, this paper educed a modified model. The model showed a high precision when the oil viscosity was below 50mPa·s testified by the current experimental datas. Under the most conditions the modified model had the hightest precision value. |
