Analysis of Rod and Tubing Eccentric Wear Mechanism in Block CD and Treatment Measures

Serious eccentric wear of tubing and rod leads to short pump inspection cycle,which seriously restricts the high-efficiency development of coalbed methane(CBM) wells.Therefore,the hole trajectory feature of the area,the mechanical property of rod string and wellbore flow regime as well as the eccentric wear mechanism and corrosion mechanism were analyzed.The hole deviation data,lifter type,fluid production and liquidity,pulverized coal content and working system were taken as a basis.A comprehensive application of tubing lining,tubing paint,various sucker rods and their fitting centralizing technology was conducted.The software for the type selection and optimization of CBM drainage-production equipment was applied.Finally,a set of optimal design template suitable for the lifting string of CBM directional wells in Area CD was screened.The application of the optimized template remarkably lengthens the pump inspection cycle,reduces the workover cost and achieves the desirable effect of application.It is suggested that research on the single-well water production capacity in the Area should be strengthened,providing the basis for the optimal design of the lifting string of CBM wells.