Eccentric Wear And Corrosion Life Prediction And Matching Selection Of Tubing In Pumping Wells

The main oil production equipment used in pumping wells include pumping unit,sucker rod and oil pump.In the process of oil production,the eccentric wear of sucker rod and tubing caused by rod buckling and well deviation,and the joint action of well fluid composition,well fluid flow and downhole temperature,etc.,lead to tubing corrosion,which becomes the main factor limiting the stability and long-term production of tubing in pumping wells.In order to overcome the influence of eccentric wear and corrosion on production,in addition to conventional N80 steel tubing,tungsten plated tubing,HDPE lined tubing and UPK lined tubing are also used in an oil production plant of Shengli Oilfield of Sinopec.Considering the practicability and cost of various types of tubing,there is no effective method to guide the selection of tubing matching for pumping wells under different working conditions.In order to help Shengli Oil Field to solve this problem,this paper considers two factors of tubing eccentric wear and corrosion,and establishes a prediction model of tubing eccentric wear and corrosion life,so as to guide the matching selection of tubing according to the service life,ensure longterm production of oil wells,reduce the production cost.In this paper,the two main failure modes of eccentric wear and corrosion of tubing in pumping wells are analyzed.the wear evaluation test and corrosion evaluation test of various types of tubing used in oil production plant are carried out,and the influence of various factors on the wear and corrosion of tubing is analyzed.At the same time,the strength evaluation model of tubing after eccentric wear and corrosion is established based on the finite element method,and the influence of eccentric wear depth and corrosion depth on the residual strength of tubing is analyzed.Based on this,the calculation model of the maximum eccentric wear and corrosion depth of tubing is established,which is the basis of calculating the eccentric wear and corrosion life of tubing.In addition,based on the wear evaluation test results,energy wear theory and the geometric relationship after eccentric wear of tubing,the calculation model of eccentric wear depth of tubing is established.According to the results of corrosion evaluation test,the calculation function of corrosion rate is fitted.Coupling the calculation model of eccentric wear depth and the calculation function of corrosion rate,taking the maximum eccentric wear corrosion depth as the critical condition,the prediction model of eccentric wear corrosion life of tubing is established.According to the prediction model of tubing eccentric wear and corrosion life,the software of tubing eccentric wear and corrosion life prediction for pumping wells is developed by using C# language,and the service life of various types of tubing under different well conditions is predicted and calculated.According to the calculation results and the field tubing long life requirements,the applicable tubing recommendation table is made.According to the well condition of the pumping well,the suitable tubing type in the recommended table can be found and the matching selection of tubing can be carried out.