The Study On Mechanism Mechanism And Countermeasure Rod Breaking Countermeasures Of Sucker

Sucker rod plays the role of power transmission in the production of pumping wells.Under the action of alternating load for a long time and periodic reciprocating motion,the sucker rod is easy to break under the complicated downhole conditions,which seriously affects oilfield crude oil output and increases the cost of well maintenance and oil cost per ton.This paper will investigate and analyze the factors which casue the sucker rod breaking to study the mechanism and the countermeasure of sucker rod breaking.Firstly,statistics and analysis are made on the influence factors of sucker rod breaking in Tahe oilfieldrespectively for the heavy and light oil wells.The results show that fatigue damage is the key factor.Due to the use of big coefficient in design,part of the submergence depth is too big,so the lower part of the 3/4"rod pumping rod will be more easily damaged in alternating loadsunder the pressure and tension influences.The statistical results show that with the increase of water content,the sucker rod breaking probability is reduced for heavy oil wells,while for the light oil wells,it is increased.And the breaking frequency is obviously higher for wells with high H₂Sconcentration than that with low.Failure experiments are made for the breaking sucker rod,and the composition and structure were respectively analyzed by metallographic microscope spectrometer.The results show that when the sucker rod is under the alternating load and periodic reciprocating movement,because of the effect of the stress and acid corrosion,the electrochemical corrosion and stress corrosion in the sucker rod surface firstlycause pit and pit cracks,and then become the source of fatigue crack,resulting in sucker rod breaking.In order to prevent the sucker rod breaking to improve its efficiency,this paper puts forward the measures of optimization design of sucker rod.To optimize the system design,theory is firstly analyzed and studied and the influence factorsare taken into consideration,design and verification system software is developed for sucker rod pumping wells.After the theory research and software development,an application example is analyzed and calculated in this paper.The optimization design of rod string on field application and the check results further verified the study and the theory on the influence factors and the optimization design.