A Study On Expandable Casing Joint By Finite Element Simulation

The design of expandable casing joint is the key and diiffcult point of the expandablecasing technology*So far there is no unified standard of the expandable casing jointparameters. By the way of theory analysis and ifnite element method, the process ofexpandable casing joint make-up, under internal pressure and carrying axial load are simulated.This paper mainly studies the affect of expandable casing joint parameters including the taper,tooth depth, carrying angle and oirentation angle to the stress of expandable casing joint beforeand atfer expansion, the expansion force needed and the physical dimension. This papermainly conducting the following conclusions:(1)Duirng and atfer the expansion process, the maximum stress of the pipe section islarger than that of the thread section. Atfer expansion process the thickness reduction ration is6.5%larger than that of the pipe section, which is3.8%. The expansion force of the pipesection (1425kN)is smaller than that of the thread section(l447kN).(2)The effect of thread parameters to the maximum stress duirng the expansion process isnot obvious.(3)The taper and orientation angle of the thread parameters have an obvious inlfuence onthe expansion force during the expansion process, while the effect of taper is greater, thebiggest difference is69,1kN. The tooth depth and carrying angle of the thread parametershave little influence on the expansion force during the expansion process.(4)The effect of taper to the maximum stress of the expandable casing joint atfer theexpansion process and thickness reduction is obvious. The expandable joint of1:18taper hasthe minimum stress atfer the expansion, thickness reduction ratio and the expansion ofrce.(5)The effect of tooth depth to the maximum stress of the expandable casing joint atferthe expansion process and thickness reduction is obvious. The expandable casing joint of1.Omm tooth depth has the minimum stress, while the joint of1.2mm tooth depth has theminimum thickness reduction ratio.(6)The effect of carrying angle to the maximum stress of the expandable casing jointatfer the expansion process and thickness reduction is obvious. The expandable casing jointof-7°carrying angle has the minimum stress, while the joint of-9°carrying angle has theminimum thickness reduction ratio. (7) The effect of oirentation angle to the maximum stress of the expandable casing jointatfer the expansion process and thickness reduction is obvious. The expandable casing jointof15。oirentation angle has the minimum stress, while the joint of15。orientation angle hasthe minimum thickness reduction ratio.In this paper, the effect of the thread parameters to the stress of expandable casing jointbefore and atfer expansion, the expansion force needed and the physical dimension means a lotto the design of the expandable casing joint.