Solving casing subsidence problems with downhole activated casing slip joints

摘要

Subsidence in chalk fields loads casing and liners with axial compression loads and results in uneven radial loading of the pipe wall. Eventually the casing or liner will fail from plastic collapse under the stress generated by the uneven radial loading combined with axial compressive load. Casing Slip Joints placed in the compacting zones can reduce the combined stress in teh corss sections thus increasing the stress level from uneven loading that can be tolerated. Current designs require an activation load of 1500,000 lbf. to initiate closing. The effect of a slip joint will be greatly improved if the Slip Joint is able to close when subjected to a small compressive load instread of the 150,000 lbf. currently required.