Study On The Mechanism Of Sucker Rod Partial-wear And The Control Measure

As the oilfield development entering into middle and later periods, the phenomenon of rod and tube partial-wear grow intensely, seriously affect oil production. Towarding the problem of rod and tube partial-wear, the domestic and international petroleum workers have made a large amount of theoretical research, having made certain achievement. Various kinds of measures anti-partial wear emerged. But because the theoretical model about the mechanism of rod and tube partial-wear was not perfect enough, and the measures anti-partial were not suit, the phenomenon of anti-partial failed still take large proportion. So, it is necessary to study further towarding the problem of rod and tube partial-wear.This article was on the basis of analysis of rod and tube partial-wear at present, having probed into the effect of oil flow and collar on the rod's force, provided the calculation model of force generated by the oil flowing in the annular space made up of sucker rod and rube (abbreviated as differential pressure force), and analyzed the influence factors of differential pressure force.Considered synthetically various force of string, have provided the calculation method of string's neutral point and axial force, analyzed the well bore factors, such as well deflection, etc. the dynamical factors, such as stroke and pumping speed, etc. the oil factors, such as viscosity, etc. have influence on the string's force. Besides, this article has proved that the differential pressure force has great influence on the polished rod load and the string's neutral point, so, the differential pressure force can't be neglected. These analysis are important for revealing the mechanism of rod and tube partial-wear of pumping well.On the basis of research on the partial-wear mechanism, this article has studied the technology anti-partial wear and related tool. The article has put forward a new technology anti-partial which utilized the principle of hydrodynamic lubrication, using tool with special structure, enabled the convergent wedgelike gap formed between rod and tube. Finally, through setting up equation of hydrodynamic lubrication and example analysis, has proved the technology anti-partial which based on the principle of hydrodynamic lubrication can prevent rod contact from tube, and can improve the repair free period of oil well.