文档介绍：摘要本文针对气体钻井过程中钻柱的动力学特性及疲劳破坏问题,对国内外有关气体钻井钻柱动力学及钻柱疲劳失效的研究成果进行了调研分析。在此基础上,通过室内模拟实验,研究了气体钻井条件下底部钻柱的运动规律及其影响因素,指出了底部钻柱可能存在的几种运动状态、产生涡动的原因、涡动发生的条件以及影响钻柱涡动的因素。建立了考虑井壁摩擦时的管柱屈曲微分方程及其求解方法,并分析了井壁摩擦、扭矩对钻柱屈曲的影响以及管柱最大转速与正弦屈曲时临界轴向力的数值关系。研究表明,当钻压一定时,底部钻柱随转速变化存在三种不同的运动状态;转速低于临界转速时正向涡动、运动状态比较稳定;在临界转速附近时无规则运动、运动状态不稳定;转速高于临界转速时反向涡动、运动状态稳定。另外,钻压、稳定器的位置及个数、井壁摩阻大小等对钻柱的运动形态也有很大的影响。在钻柱上安装滑套式稳定器可以有效改善钻柱的稳定性。剧烈振动是造成气体钻井钻具失效的重要原因。文中分别讨论了钻柱横向振动、扭转振动和纵向振动固有频率的计算方法,重点分析了钻柱横向共振的发生及危害,给出了确定钻柱临界转速的方法。关键词:气体钻井,钻柱运动特性,管柱屈曲,正向涡动,反向涡动,钻柱失效 Study on Dynamic Characte“stics and Failure Mechanism ofDrillString inAirDrilling Wang Yunfeng(Oil&Gas WellEngineering) Directed by Professor Guan Zhichuall Abstract Focused on theissueofdynamic characteristics and fatigue failure ofdrillingstring in gasdrilling,the paper makes investigation analysis on research results of theissue athome and thisbasis,the articlecarries out study on drillstringmovement law and its influencing factors by thesimulation experiment ofBHA motion state,and points outthe several possible kinds ofBHA motion states,the causesand conditions oftubularwhirling and theinfluencing factors thesis alsoestablishes the buckling differential equations谢t}l friction,presents itssolutionmethod,analyses theeffect offrictionandtorque on tubularbuckling and outlines thenumerical relations between themaximum speed and criticalaxialforce when drillstrings are insinusoidalbuckling research shows that. thereare three different BHA motion states atspecified drillingpressure which respectively correspond、析m that:a es intostablepositive whirling under criticalrotate speed,irregular and unstable movement of BHA appears atcriticalspeed,when rotatespeed exceeds criticalspeed adrillstring forms stable reverse ’S more,theanalysis also indicates thatthese factors such asdrilling pressure,the position andnumber of centralizer,friction ofborehole wall and the location andnumber ofsliding sleeve have a greatimpact on motion state of