The Study Of Lighten Technology And Composite Design For Sucker Rod In Deep Well

At present, China’s major oil fields have moved into the stage of depth development and the water cut in some oil well has even reached 90%. Deepening pump depth has become the inevitable trend, as the dropping of working fluid level, the reducing of energy and the rising of water content. At the same time, the exploitation range is greatly expanded. The exploration object is shifting from productive layers to the poor permeability. Due to the poor physical property, low-liquid, the depth of pump, and the lagged technology, the system efficiency of oil production systems is low, and the total benefit is seriously influenced. So it has important theoretical and practical significance for the development of petroleum industry in China, that study the Key technology of Oil pumping units at the middle and later metaphase, form the design method and the technology of related equipment, solve the problem of the polished rod load in deep well.Based on the analysis of dynamic characteristics of beam pumping unit and the characteristic of suspension point load, ascertained the main influencing factors of the polished rod load; Analyzed the Lightening affection and bearing capacity of the hollow sucker rod, by calculated and contrasted the parameters, for example the polished rod load, torque, strength stress and so on, between hollow sucker rod in various sizes and solid sucker rod at a variety of operating conditions; Designed and analyzed the reasonable installation position of load-reduce device, according the study of structure and working principle; Established the combination mathematical model of the lightening device-compound rod string-small diameter pump.Modified the formula of the polished rod load.Using the equal-intensity formed the combination design method with lightening device, taking the max polished rod load as objective function, to meet the strength requirements of 4000 m deep; Using the Visual Basic visualization program compiled the corresponding simulation program of the optimum design.According to the comparative analysis and calculation, it could lower the max polished rod load by 19.67% to 30.58%, the peak of crankshaft net torque by 11.3% to 21.95%, the peak of balance weight by 28.57% to 37.03%, by using the hollow sucker rod at 1000-meter well; The result of simulation program shows that when the plunger diameter is 28 mm or 38 mm, the max polished rod loads are only 49.897 kN, 60.013 kN, the stroke loss are 0.635 m, 1.283 m at 3000-meter well; And the max polished rod loads are only 70.231 kN, 82.162 kN, the stroke loss are 1.191 m, 2.273 m at 4000-meter well. The theoretical results of 6 oil wells are basically consistent with test results. Verified the theory that hollow sucker rod could reduce polished rod loads, and the veracity of composite design method and the simulation program.