Mechanical Analysis Of Coiled Tubing Operation String

Coiled tubing operation string is made up by coiled tubing and underground work tools.It is widely used in various downhole work fields of Oil and Gas well.The application key factors of coiled tubing operation string are running depth accuracy and operation safety.Running depth accuracy includes running depth calculation and the effect of axial length change to running depth.It involves operating characteristics of coiled tubing operation string、buckling behavior、axial force distribution、deformation and so on.It is related to the success of underground working,and will affect the economic benefit of production.Therefore,it is necessary to study the mechanical analysis of coiled tubing operation string.This paper focuses on the study of running depth accuracy of coiled tubing operation string.At first,operating characteristics of coiled tubing operation string are analyzed.Combining with actual examples,it also explores light and soft features、residual bending at the before entering well、change rule of diameter increase and card position calculation.Subsequently,it also studies buckling behaviors of coiled tubing operation string in different sections in horizontal well,and provides calculation models of buckling critical load.At the same time,calculation models of axial force of coiled tubing operation string in two dimension and three dimension well are established.It also provides strength analytical model and VonMises stree calculation.According to the relationship of friction、buckling and axial force,it provides axial force calculation models of coiled tubing operation string in horizontal well,and detaily studies axial forcr distribution,especially for lock-up point.Finally,it provides axial deformation calculation methods of operation string.The methods are related to axial force、pressure、temperature and spiral buckling.WELLPLAN is uesd to analyze stress change of coiled tubing hydraulic sandblasting operation string during tripping in and out.