Abstract: The fault occurring probability of sucker pumping system of directional wells is higher than that of straight wells.The fault diagnosis technique for sucker-rod pumping system of straight wells can not be applied to that of directional wells for their 3-D well curve,or it will result in a big error.Existing mechanical analysis about directional well systems only consider 1-D vertical vibrations of sucker rod,fluid,and tube,or consider 3-D vibration of sucker rod only.This paper presents a FEM and FFM method to analyze 3-D couple vibrations of rod,fluid and tube,the three systems of directional well.The result calculated with this method gives precise pump displacement-load plots.The fault diagnosis about pumping system according to these plots has achieved good results in pump checking.

Key words: directional well, sucker-rod pumping system, finite element method

摘要： 定向井和水平井的井下装置发生故障的可能性比直井要大得多.如采用对直井的故障诊断技术对定向井进行诊断,势必带来较大的误差,甚至无法诊断.已有的一些对定向井有杆抽油系统力学分析中或只考虑杆管液三个系统的垂向一维振动,或只考虑抽油杆一个系统的三维振动.本文根据定向井井身为空间三维曲线的特点,考虑抽油杆、油管和环空波柱三个系统在生产过程中的三维空间振动耦合,对三个系统进行一定的简化,分别建立力学模型,全面分析,采用有限元法和有限差分法相结合的方法统一迭代求解,由井口实测光杆示功图计算出较为准确的抽油泵的井下功图,为对其进行故障诊断提供了准确的依据.分析诊断结果与检泵结果符合良好.

关键词: 定向井, 有杆泵, 抽油系统, 有限元法