同心双管柱受力分析及变形计算

在油气井冲砂、排酸等井下作业中,同心双管柱具有广阔的应用前景。根据流体力学、弹性力学等理论建立了同心双管柱的力学、数学模型,比较全面地考虑了同心双管柱作业时受到的各种作用因素,推导出同心双管柱变形量的计算方法。计算结果表明,同心双管柱在压差、浮重、摩擦力、温差和膨胀综合作用下发生变形,对其使用和安全性能产生影响;在实际工程中,由于套管和管柱的摩擦作用以及井斜角的影响,同心双管柱的实际变形量要小于理论计算值;当外油管缩短内油管伸长达到一定值时,内油管发生屈曲变形,需要做管柱的变形补偿设计。

Force Analysis and Deformation Calculation of Concentric Double String

The concentric double string has broad prospects of application in oil and gas well downhole operations such as sand washing and acid discharge.The mechanical and mathematical models of concentric double string were established according to hydrodynamic and elastomechanical theories.The influencing factors of the string in operation were considered comprehensively.The calculation method for the string deformation was derived.The calculation shows that the deformation of the string is caused by the effects of pressure difference,submerged weight,frictional force,temperature difference and expansion.The deformation affects the application and safety performance of the string.The actual deformation of the string is less than that of theoretical calculation in practical engineering due to the effects of the friction between casing and string as well as well deflection.When outer tubing shortening and inner tubing lengthening reach a certain value,the inner tubing will undergo buckling deformation.Therefore,the compensation design of string deformation should be conducted.