Optimal Design For Ultra-high Strength Sucker Rods String

Ultra-high strength sucker rods has Ultra tensile strength and fatigue strength,which is suitable for heavy?overweight loads?non-corrosive or slightly corrosive wells.Its application in major oil fields is more and more widely in recent years,However,the mechanical properties of ultra-high strength sucker rods has changed compared with common sucker rods,which needs to make further optimization for combination design of the rod string.The paper is based on the fatigue performance and tensile test of sucker rods,establishes the calculation method of allowable stress,which improves from API methods,and lays the foundation for the combination design of sucker rods string.Then it analyzes the situation of stress for sucker rods in the three dimensional hole,and uses infinitesimal method to calculate axial load and stress of sucker rods string from bottom to point by node,results shows that the model has high precision.Then it sets up efficiency of pump as optimization object,and changing combination of swabbing parameters is to get corresponding combination and pump efficiency under different swabbing parameter,and gets optimal combination by comparing of pump efficiencies.Besides,the paper considers the impacts of stabilizer on load,basing on stress analysis after adding stabilizer and combining three-dimensional deformation analysis of sucker rod,finally it establishes the model to calculate the space for stabilizer in different section of the well.It develops the software of optimum design for ultra-high Strength sucker rod string by Visual Basic6.0,which is suitable for directional well.By using the software,the stress of sucker rod string after adding stabilizer is calculated,take this as foundation,optimization design is carried out.Result shows that pump efficiency is improved by 16.574% from49.459% to 66.033% and stress range ratiois improved by 3.21% from 0.499 to 0.515.The number of the installation of the stabilizer is 9 less than that before the design.Optimization effect is proved to be good.The application shows that the software can provide convenience for the optimization design of sucker rod.