Research On Expanding Rule Of Bellows

Expandable convoluted tubing technique can solve many problems such as loss circulation formation,water zone,high pressure formation and easy,collision well section.It is a glorious prospect in the application field.This thesis focuses on the finite element analysis model for the bellows of ?215.9mm is developed using ABAQUS program.Considering the variation of bellows material,bellows thickness,boreholes diameter and borehole curvature.The purpose of this paper is to simulate the expansion process of bellows under construction pressure.It is concluded that the hydraulic expansion law of bellows in vertical wells,horizontal wells and curve welsl.Firstly,the influence factors of bellows expansion are introduced.Including bellows material including YS1,YS2,YS3,bellows thickness including 7mm,8mm,9mm,boreholes diamters including 230mm-245 mm,boreholes curvature including 10°/30 m,20°/30 m,30°/30 m.According to the bellows string structure selection,bellows connection mode is threaded connection and welding.The“8”section shape is chosen according to expanding easiness and field application.Secondly,the expansion model of bellows in vertical well is established to find out the deformation and stress strain analysis of the bellows after the expansion.It is concluded that the maximum stress of the bellows is located at the peaks of the outer wall.In the process of expansion,research on the influence of the diameter of boreholes,the thickness of the bellows and the bellows material on expanding rule.Results show: When the bellows thickness is 7mm,the bellows expansion is good.The bigger the borehole diameter is,the easier the bellows expands.When the borehole diameter is 237 mm,240mm,the expansion of the bellows is good.When bellows material is YS2,bellows expansion is relatively good in vertical wells.At the same time,this thesis analyzed collapse resistance and internal pressure strength.The results show that the effect of the out of roundness on the collapse resistance of bellows is very large.Finally,the model of the horizontal wells and the expansion bellows is established.Study on the drilling and expansion process of bellows.Research on expansion rule of bellows.Results show: The borehole curvature has little effect on the variation of the diameter,the long axis,throughs and peaks.It is similar to the expanding rule of the vertical well that bellows thickness,bellows material and boreholes diameters influence on Expanding Rule of Bellows This is also true for horizontal wells.Through the evaluation of weld,results show: The stress of the weld is greater than that of the bellows,and the strain is larger than that of the tube.But less than the pipe elongation 0.33.So welds is safe.