Research Of Grade H Sucker Rods String Mechanical Properties And Its Design Method

Grade H sucker rods has Ultra-high tensile strength and fatigue strength, suitable forheavy, overweight loads, non-corrosive or slightly corrosive wells. In recent years with abetter understanding of it, its application in major oil fields is more and more widely.However, in practice there are still issues such as fatigue fracture, which reflects the design ofthe sucker rods string there are some flaws, and it needs to be further improved.In the paper, from the calculation of allowable stress and check of fatigue strength thesetwo angles, for the determination of allowable stress made the key research with grade Hsucker rods tensile test and fatigue test for the foundation and based on the theory of fatigue.By means of analyzing rods string work force in directional well, with micro element methodby nodes to calculate axial load and stress of arbitrary cross section, analyzed the case of twodirectional well, the results show that the model has higher precision. On the basis of thismodel, with the improvement of allowable stress and equal strength design criterion for theprinciple, the И A Мистер and the modified API methods were used for design grade Hsucker rods string. Meanwhile, the existing commonly used two kinds of rods string designmethods were analyzed and compared, to obtain a more suitable method of grade H suckerrods–the modified API method. In addition, according to the stress state of sucker rodsstring in directional wells, based on the И A Мистер method and the modified APImethod,compiled for directional well sucker rods string design software by using visual basicprogram language.And finally through the example of directional well sucker rods stringdesign with grade H and D respectively, analyzed and contrasted the working status of designresults, compared the optimal design objective function, analyzed the advantages anddisadvantages of sucker rods string design with grade H and D, and put forward the suitablemethod and suggestion for grade H sucker rods string design in oilfield applications.