旋转抽油杆柱扭转振动固有频率分析

Analysis of Twisting Vibration Eigenfrequencies of Rotary Sucher-rod String

在对旋转抽油杆柱的扭转振动分析的基础上 ,给出了各阶扭转振动固有特性参数的计算式 .实例计算结果表明 :螺杆泵采油系统在 70 0～ 1 80 0 m的正常下泵深度时 ,常用的单级和二级抽油杆柱的前五阶扭转振动固有频率在 2 6～ 6 0 8r/min,覆盖了螺杆泵采油系统的工作转速区 (6 5～3 5 0 r/min) ,这完全不同于有杆泵采油系统 .指出 :在选定螺杆泵采油系统的工作转速时 ,应将杆柱的前五阶扭转振动固有频率对应的转速作为约束条件 ,以避开该转速范围 ;对于级次杆柱的高阶固有频率 ,由于其频率相对单级杆柱的增减幅值在 2 .1 %～ 5 .2 %之间 ,可近似按单级杆柱考虑 .

On the basis of the analysis of the twisting vibration of rotary sucher-rod string, a formula of calculating every harmonic vibration eigenfrequency is presented. The calculated result of a instance shows that, when the setting depth of a pump is in the range of 700~1800m, five lower harmonic twisting vibration eigenfrequencies of a single-diameter or two-diameter sucher-rod string are in 26~608 r/min, in which the working rotary speed range (65~350r/min) of screw pump producing systems is completely included. This is different from the case of suck rod pump producing systems. Therefore, when the working rotary speed of a screw pump producing system is selected, not only are the base frequency but also the higher harmonic eigenfrequencies of the sucker-rod string considered. The higher harmonic eigenfrequencies of a two-diameter sucker-rod string can be approximately substituted with those of a correspondence single-diameter sucker-rod string because the difference between the former and the latter is only 2.1%~5.2%. The data in the paper can be used for guiding the matching of sucker rod combination with rotary speed of a screw pump producing system.