水驱高含水油井杆管偏磨原因的力学分析

建立了抽油机井杆管偏磨原因力学分析的力学模型。给出了垂直油井杆管偏磨临界轴向压力的计算公式和抽油杆柱轴向分布力的模拟方法 ;推导了供液不足油井液击力的计算公式 ,改进了柱塞下行阻力的计算方法。系统分析了含水与沉没度对杆管偏磨临界轴向压力与柱塞下行阻力的影响。分析结果表明 :(1)高含水油井在低沉没度下运行会明显加剧抽油杆柱的轴向振动 ,降低杆管偏磨的临界轴向压力 ;(2 )对于高含水低沉没度运行的油井 ,若油井供液不足将使柱塞下冲程泵内产生液击 ,柱塞下行阻力会明显增加。因此 ,高含水油井在低沉没度下运行时 ,抽油杆柱轴向振动的加剧或液击都会严重恶化抽油杆柱的受力或直接导致杆管产生偏磨

Research on the mechanical causes of the rod string and tubing wear of rod-pumped wells in water controlled fields

The mechanical model of the rod string and tubing wear of rod-pumped wells is established. The calculating formula of critical axial load of rod stringand tubing wear is presented,and the simulating method of axial distributing load of the rod string is set up by the wave equation of the rod string. With the liquid shock load occuring in the low submergence depth being set up, the axial load in the down stroke of the plunger is established. The influences of water cut in well fluid and pump submergence on the wear of the rod string and tubing are analyzed systematically. The result of the investigation shows that: (1) the axial vibration of the rod string may be intensified while the subsurface pump runs with low submergence depth in high water cut wells, and the critical axial load of rod and tubing wear will be reduced; (2) when the pump barrel could not be filled up with well fluid, the liquid s,iock will occur, and the liquid shock load will make the down stroke axial load of the plunger increase. Therefore both the intensity of the axial vibration of the rod string and liquid slugging may cause the wear of the rod string and tubing.