Research On Self-Aligning Packing Box And Anti-Friction Wear-Resistant Sealing Packing For Pumping Unit Wells

As oil wells in our country enter the late stage of cut exploitation with high moisture content,the problem of eccentric wear of pumping units has become increasingly prominent.As the wellhead sealing device of the rod pumping unit,the packing box is the weakest part of the whole machine,and its sealing performance is affected by eccentric wear.Packing box mainly adopts packing sealing method,but the existing rubber sealing materials cannot satisfy its working environment.In order to improve the poor wear resistance of rubber seal packing materials and partial wear of the packing and polished rod of the pumping unit,a self-aligning energy-saving packing box for pumping wells and a new kind of nitrile rubber special materials for packing box with anti-friction and wear-resistant was developed.The research content includes:Analyzing the reasons for the poor wear resistance of the existing NBR packing,GF and flake graphite was added on the basis of NBR,and 16 groups of NBR/GF/graphite composite materials with different ratios based on the orthogonal experiment method was prepared.Of which the water absorption,hardness,tensile strength,compressive strength,friction coefficient and wear rate was measured,the friction surface morphology of some specimens and their counterparts were observed,and their wear mechanism in water environment was analyzed.Based on regression analysis of the experimental results with SPSS,the order of the influence of GF and graphite mass fractions on the properties of composite materials was analyzed.Regression model of friction coefficient and wear rate was established and then to select the optimal composite material refer to the actual conditions.Analyzing the reasons for the partial wear of the ordinary packing box,to improve the structure of the ordinary packing box and ball head structure was adopted to make axis of polished rod and the packing to be consistent,and self-aligning energy-saving packing box was designed.Mathematical models of packing axial stress,internal and external pressure and packing friction power under medium working conditions are established to calculate the friction power of modified packing and ordinary packing based on thick-walled tube theory to calculate the friction power of modified packing and ordinary packing.The results show that the friction power of modified packing is 53.5% lower than that of unmodified packing under the same internal pressure,which means the modified packing has a significant energy saving effect.The friction force model of ordinary packing box and self-aligning energy-saving packing box was established based on Abaqus,and the friction power of two kinds of packing box was calculated.The results show that the friction power of the self-aligning energy-saving packing box is 52.9% lower than that of the ordinary packing box,which means the self-aligning energy-saving packing box has a significant energy saving effect.