高压高产气井完井管柱振动特性及安全分析

Vibration Characteristics and Safety Analysis of Completion String in High Pressure and High Gas Rate Well

目前针对油气井完井管柱振动的研究没有考虑气体诱发管柱横向和纵向耦合情况,而实际管柱与管内流体存在横向和纵向的相互影响。为此,对完井管柱系统流固耦合振动响应进行初步分析和探索,建立了气井完井管柱流固耦合模型,编制了相应的Fortran程序,并结合华北油田某完井管柱现场数据,讨论了产气量、井口压力和气体密度等参数对管柱振动特性的影响。研究结果表明:在开阀门的瞬间,完井管柱产生剧烈振动,随着产出气体压力逐渐稳定以及管柱自身的刚度具有抵抗变形的能力,管柱的振动呈现逐渐衰减的趋势;随着产气量的增加或井口压力的降低,气体对管柱的作用力增大,管柱振动产生的变形增大;当气体密度增加时,管柱与气体之间的摩擦耦合作用加剧,管柱振动增强。研究结果对于降低完井管柱的振动和保护管柱安全具有重要意义。

The present research on vibration of completion string in oil and gas wells does not consider the lateral and longitudinal coupling of string induced by gas, however, actually, the string and the fluid in the pipe have lateral and longitudinal interactions. Therefore, in this paper, we preliminarily analyzed and explored the fluid-structure coupling vibration response of the completion string system, built the fluid-structure coupling model of completion string in gas wells, compiled corresponding Fortran program, and combined with the field data of a completion string in Huabei Oilfield, discussed the influences of gas production, wellhead pressure and gas density on the vibration characteristics of the string. The research results show that at the moment of opening the valve, the completion string produces severe vibration;as the pressure of produced gas gradually becomes stable and the stiffness of the string itself has the ability for resistance to deformation, the vibration of the string shows a gradual attenuation trend;as the gas production increases or the wellhead pressure decreases, the force of gas acting on the string increases, and the deformation resulted from string vibration increases;when the gas density increases, the friction coupling between the string and the gas intensifies, and the vibration of the string increases. The research results are of great significance for reducing vibration of completion string and protecting safety of the string.