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Compression relief mechanism for retrievable packers

IP.com Disclosure Number: IPCOM000243091D
Publication Date: 2015-Sep-14
Document File: 8 page(s) / 1M

Publishing Venue

The IP.com Prior Art Database

Abstract

Cut-to-release and pull-to-release packers are widely used in completion strings for their ease of retrieval. However, when there are compression loads in the tubing below these packers, it poses a potential threat to the packers’ retrievability as the packer’s outer components do not have space to slide down to unset the packer. The disclosed invention tackles this problem of retrievable packers not being able to release when set with tailpipe compression below the packer. This has been achieved by adding a simple ‘compression relief mechanism’ at the bottom of the retrievable packer. While the packer is being set, a gap “GAP M” is generated in the lower section of the packer. This gap relieves any tailpipe compression acting from underneath the packer by allowing room for the packer to take in unexpected compression/tension/movements originating from beneath the packer. Now, during release after cutting the mandrel or a straight-pull, the outer components can slide down without being obstructed by the compressive loads from below as the compressive loads have been absorbed by the “GAP M” which was created after the packer was set. Thus, the packer releases as intended.

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Compression relief mechanism for retrievable packers

Abstract

Cut-to-release and pull-to-release packers are widely used in completion strings for their ease of retrieval. However, when there are compression loads in the tubing below these packers, it poses a potential threat to the packers' retrievability as the packer's outer components do not have space to slide down to unset the packer. The disclosed invention tackles this problem of retrievable packers not being able to release when set with tailpipe compression below the packer.

This has been achieved by adding a simple 'compression relief mechanism' at the bottom of the retrievable packer. While the packer is being set, a gap "GAP M" is generated in the lower section of the packer. This gap relieves any tailpipe compression acting from underneath the packer by allowing room for the packer to take in unexpected compression/tension/movements originating from beneath the packer. Now, during release after cutting the mandrel or a straight-pull, the outer components can slide down without being obstructed by the compressive loads from below as the compressive loads have been absorbed by the "GAP M" which was created after the packer was set. Thus, the packer releases as intended.

Purpose of the Invention

Currently, one of the common methods of unsetting retrievable production packers is to apply a straight-pull on the tubing string. Alternatively, another common release method is the cut-to-release method where a chemical/mechanical cutter is used to cut through the packer mandrel's thickness at a specific section. In both these methods, the connection between the outer components of the packer (including the slips/wedges/elements) and the core mandrel of the packer is broken. Breaking this connection allows room for these outer components to move down, thereby, giving space for the slips to retract back and the elements to spring back to their original shape.

While this method is fairly reliable and commonly used in retrievable packers across the industry, there is a potential for the packer not being able to release when there is tailpipe compression below the packer. This tailpipe compression may occur when the packer is set on top of another packer or liner hanger. Tail pipe compression may also occur when certain operations/well-scenarios unexpectedly generate compression below the packer. When the packer is set with compression below it, upon triggering the release mechanism (pull-to-release or cut-to-release), the pre-stored compressive forces below the packer do not allow the outer components to drop down. Thus, there would not be any room for the wedges to move down, thereby, preventing the slips from retracting as well as stopping the elements from returning to their original shape. The packer is essentially permanently set and irretrievable in such a case. If such a scenario occurs, it can be very cumbersome to retrieve the packer via milling & fishing, and the non-p...