Research The Capability Of Loading Resistance On Two Horsehead Beam Pumping Units

Owing to its excellent performance, special beam pumping units(also called as two horsehead pumping units) is widely used in oil fields at present. There is some difference between special beam pumping units and conventional beam pumping units. The girder beam back arm of special ones is cranked out with a variety radius circular arc shape and the radius can be changed under some rules; additionally, the girder back arm is connected with the beam by flexible rope. The field application shows that special beam pumping units is as firm, credible and convenient to maintain as conventional units, also running calmly with less additional load, longer stroke, better balance effect, lower energy consume, and higher combined efficiency than conventional ones.At the same time, the stress of the beam structure is significantly affected by the type and position of the connection between rear horsehead and beam. There are many accidents arisen from the local girder damage, so the field application is restricted greatly.A mechanics model of the two horsehead pumping units is established in this thesis. Through the finite element analysis and girder beam stress measurement under different operating mode, visual curves of girder distortion and stress distribution are obtained, the position where maximum stress occurred are determined, then the intension analysis and rigidity analysis are carried out. It is found that the intensity check and safety factor commend methods offered by API to design girder beam of conventional pumping units are not entirely applicable for special beam pumping units, because it is not considered that the effect of connecting form between rear horsehead and girder beam on girder structure stress. The girder beam reconstruction of the special beam pumping units is designed in this paper. The girder structure design is improved based on the girder beam stress analysis. Then the dynamic stress testing of newly designed girder and rear horsehead is carried out, the stress status investigated, and the rationality of the structure design evaluated.It is obvious that the effects of connection between the rear horsehead and girder beam on structure stress should be investigated, which is important to improve the method for designing the girder beam of two horse head pumping units. Consequently, the production is safeguarded, and the design theory of pumping units enriched. In this paper, the deficiency in designing the girder beam of two horse head pumping units is made up by improving the design method. The result of this paper is significant for enhancing the performance of special beam pumping units and the safety of the pumping units used in oil production, and extending the application of the special beam pumping units.