Study On Flow-Pattern Transitions In Gas-Liquid Two Phase Flow And Wax Deposition In Wellbores

Gas-Liquid two phase flow in wellbores is the foundation of chosing ways of oil pumping. It is also a problem which has not been solved properly in thoery for a long time. Grasping the characteristic of specific flow pattern and the transiton mechanism for different flow pattern is helpful to set up a accurate two-phase model, which can nicely predict the flow law for gas-liquid mixture and guide the oil production effectively.Most of produced crude oil in our country is high wax oil. The wax and solid phase deposition has serious influence on oil & gas production. A accurate wax deposition model can provide a useful scientific proof to wax removal and wax inhibition, which is a significant research topic in oil industry.In this paper, the characteristic and transition mechanism of different flow pattern is summarized, and a new transition criterion is listed. Based on the theory of two phase flow mechanics and heat transfer, a model of temperature and pressure computation for two–phase flow is thus derived. Then some evalution of several common two-phase model is made on the continuty of flow pressure gradient and liquid holdup in the transition region. The influence of pipe diameter, angle of inclination and fluid property on flow pattern transition is analyzed. In additional, the wax deposition mechanism is researched and a model for predicting cloud point temperature is set up. The wax precipitation point is obtained by above model. And the influencing factor that affect wax deposition is ananlyzed.