Mechanical Analysis Of The String In The Setting And Unsealing Process Of The Packer In Deep Inclined Wells

In the process of downhole operation,it often has injection string broken,rupture and permanent spiral bending,packer seal,seal leakage and slippage and other underground work accident.The downhole accidents of water injection string is the important cause of helical buckling.Different equilibrium,injection string mechanics state are also quite different.Based on the deep inclined layered water injection string as the research object,in the process of packer setting and unlock the effect of axial force and deformation of tubing string mechanics analysis.Mainly includes the packer setting,unlock principle and operating mode change is analyzed,and the basic effect of water injection string including ballooning effect,temperature effect and tubing string in such as gravity,fluid pressure conditions of hydraulic axial force and deformation are analyzed;And the mechanics analysis of packer force and checking formula for example calculation,to analyze its reliability.Finally we get the following conclusions:1,In the process of injection Wells setting,under the certain pressure-out,string axial force increases with the increase of well depth from tension to compression;In tubing size and material,the axial force rate changing with vertical deep basic is a linear relationship.It is not difficult to find from the vertical section to stabilization period,axial force change with well depth is gradually reduced,and the different Wells specific need to calculate.2,In the process of injection Wells setting,under the certain pressure-out,deformation of tubing string increases with well depth change.Upper tensile string,deformation and elongation increases with well depth gradually;The lower cylinder compression,shortening deformation and increases with well depth gradually.3,In the packer,due to the function of the piston force,the axial force of here change is bigger,should focus on its strength and reliability.4,The string unlock packer,string of dangerous point in the well’s mouth,as long as the string in the well failure didn’t happen,the downhole string will not be pulled apart or cause drag mark.5,Using rotating unlock packer,the string of maximum torque at the mouth of the well,so rotating unsealed,string failure does not occur as long as the mouth of the well,the entire string failure will happen,6,By the working condition of rotating unlock string is hanging heavy rotate under the action of load and the column subjected to axial force and torque at the same time.7,Friction coefficient of load and torque on the mouth of the well have different degrees of influence,therefore,no matter which kind of unlock packer adopts way of calculating wellhead applied load should fully consider the influence of friction coefficient.8,In the actual forecast work string and in the process,as a result of borehole trajectory,the influence of factors such as temperature and sand,oil casing friction coefficient is more difficult to determine,therefore,Suggestions in the process of practical application of the same first unlock process of some Wells in the area of the measured,draw the corresponding friction factor,then unlock force projections for other Wells,in order to improve the prediction precision.