Influence Of Intermediate Packer On The Mechanical Properties Of Multi-packer String In Horizontal Well

In the process of horizontal well oil test and well completion,the tubular string may appear collapse,rupture and other accidents when the multi-packer string of horizontal well subjected to greater axial force.Because of the research on the effect of packer on horizontal well pipe string is relatively few.So,in order to learn the influence of packer on the mechanical properties of multi-packer string in horizontal well,this paper analyzed the stress of multi-packer string based on the theory of Material Mechanics when the intermediate packer has limited movement.Firstly,the spatial mechanics model of pipe string in horizontal well was established by analytic method and space geometry theory.The formula calculating of axial force and lateral force on multi-packer string in horizontal well was derived,and analyzed the mechanical properties of the tubular string by using mechanical analysis software of horizontal well string in the process of lifting and lowering.The analysis result shows that,the axial force of pipe string increase first and then decrease with well depth in lowering;in the process of lifting,the axial force decrease with linearity;the string lateral force on the bending and dog-leg section appears the phenomenon of rapid increase,and tends to be constant in the horizontal section.Secondly,the mechanics model of multi-packer string in horizontal well was established by using the vertical and horizontal bending beam theory.The calculation method of multi-packer string when the intermediate packer has limited movement,and the stress change of the tubular string is analyzed.According to this method,the numerical examples are analyzed.The analysis result shows that,the axial stress of multi-packer in horizontal well is proportional to the distance from the intermediate packer when the intermediate packer has limited movement,the maximum axial stress and deflection of tubular string in the moving direction of packer is increased,and the opposite direction is reduced.Finally,this paper summarized the stress changes rule of multi-packer string in horizontal well in the process of lifting,lowering and intermediate packer has limited movement.It provides reference for the safety application of multi-packer string in horizontal well.