Helical Buckling of Tubing Sealed in Packers

Abstract

Most gas wells and flowing oil 'Wells are completed and treated through a string of tubing and a packer. Changes in temperature and in pressure inside or outside the tubing will: (1) if free motion of the tubing inside the packer is permitted, increase or decrease the length of the tubing; or (2) if free motion is prevented, induce forces in the tubing and on the packer. If pressure inside the tubing is greater than outside, the tubing may buckle helically even in the presence of a packer-to-tubing tension. The tubing will always buckle, and much more severely, if free motion is permitted. The buckling may be prevented by pulling the tubing in sufficient tension.