高压气井生产管柱横向振动特性分析

Analysis on Lateral Vibration Features of Production String in High Pressure Gas Wells

高压气井生产管柱内流体的流动会诱发管柱振动,管柱振动会导致其疲劳、磨损甚至破裂,影响气井正常生产。结合油田现场实际,在考虑管柱重力的情况下,研究了高压气井生产管柱的横向振动特性。运用哈密顿原理,建立了包含生产管柱轴向力、管内流体流速和管内外流体压力等因素的生产管柱横向振动模型。运用伽辽金方法求解模型,计算并讨论了管柱重力、气井产量、井底压力和管柱底端轴向力等参数对油管振动频率及稳定性的影响。研究结果表明,管柱重力是生产管柱振动分析中不可忽略的因素;生产管柱的振动频率随着产量、井底压力以及轴向压力的增大而降低,其中井底压力和轴向压力对管柱振动频率的影响较大,产量的影响较小。

The fluid flow in production string in high pressure gas wells will result in string vibration,which may lead to string fatigue, abrasion or even fracturing, thus impacting the normal production of gas wells. Combined with oilfield practices and taking string gravity into consideration,the lateral vibration features of strings in high pressure gas wells have been studied. By applying Hamilton principle,lateral vibration model of production strings with axial force,in-string fluid velocity and in-/ out-string fluid pressure taken into consideration has been established. With the resolution model of Galerkin method,parameters such as string gravity,production of gas wells,bottomhole pressure and axial force at the bottom of string have been calculated and their effects on vibrationfrequency and stability have been discussed. The research results indicate that the string gravity is an ineligible factor in the analysis of vibration of production string; the vibration frequency of production string will decrease with the increase of production,bottomhole pressure and axial pressure; however,the effect of bottomhole pressure and axial pressure on vibration frequency is larger than production.