Dynamic Experiment On Waxing Of Oil Well And Prediction Model In The Bohai Oilfield

There is a serious and extensive problem in Bohai oil field:about 42 wells in the9 oilfields of Bohai Sea have the problem of wax deposition.The average loss in single well is about 47.8 m3/d due to the wax deposition.Waxing affects the production rate of oil well,which results in an average reduction in production rate of 18%and cumulative loss of yield is about 15.3×10~4 m3in one year.Wax deposition influences on the oil production efficiency in two aspects:Firstly,wax deposition led to the cross-sectional area of the wellbore decreases,which increases the fluid flow resistance,the oil system has an additional pressure drop;Second ly,seriously affects the platform equipment operation normally,increasing the load of equipment,which has brought a great impact on the production and collection of crude oil.Effective prediction of wax deposition has become a serious problem that must be solved.In this paper,a set of experimental equipment for the dynamic waxing of crude oil were designed.The experiment device has the function of evaluating the dynamic waxing of the whole wellbore and the effect of different waxy chemical agents under different influencing factors.The influence of different factors on the wax deposition were studied.The factors influencing the wax deposition were analyzed quantitatively.Finally,the actual production examples were evaluated.Based on the regression data of experiment,a new dynamic model of waxing was established for Bohai oilfield.As to the new model of wax deposition prediction,the critical interference waxing quantity is defined,whose calculation model is also designed.The practical data are used to analyze the influence of the critical interference.