Research On The Influencing Factors Of Setting Depth In Coiled Tubing Downhole Operation

With the improvement of the properties of steel,the maximum setting depth of coiled tubing is constantly being refreshed.In order to prevent accidents of buckling failure during the process of working,we should judge whether the coiled tubing can go down safely before operation,and select a coiled tubing parameter reasonably to achieve a safe and economical operation process.There is a residual bending of a continuous tube before underground.The residual bending affects the setting depth of the coiled tubing,so the analysis of the influence factors of the setting depth is more accurate and reasonable in consideration of the residual bending of the coiled tubing.This paper studies the following four aspects of the influencing factors of coiled tubing’s setting depth.(1)The two dimensional axial force calculation model of the coiled tubing in the curved well was derived,and the relation between the axial force and the angle was obtained.(2)The ABAQUS is used to simulate the operation process of the coiled tubing on the ground,and the sinusoidal residual bending form of the four operating conditions is obtained.(3)The finite element software ABAQUS is used to analyze the buckling failure process of the coiled tubing,and find out the critical buckling failure load of the coiled tubing,and study the influence of wall thickness,diameter,initial configuration and wellbore gap on critical buckling failure load.(4)Different wells have different well conditions,each factor has different influence on the setting depth.This paper selects a specific logging data to fit well trajectory,and calculates the influence of coiled tubing’s diameter,wall thickness,initial configuration,working pressure and friction coefficient on the setting depth.