Retrievable Packer Seal Pressure Relaxation via Mandrel Cut
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing retrievable packers or plugs face issues with binding slips due to residual rubber pressure in the sealing element assembly during release, as the force holding the seal assembly in the set position can be too strong, making it difficult to relieve pressure effectively.
Innovation Solution
A mandrel cut is implemented to raise a portion above the cut, allowing a wedge cone to retract and create space for residual rubber pressure to push the locking member radially inward, using collet heads with a radially inward bias to assist in retraction and relieve pressure before slip cones are moved relative to the slips.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the lock ring is defeated to release the outer assembly, then the packer can be retrieved, but the residual rubber pressure causes the slips to bind
Solution Approach 1:
The patent applies preliminary action by releasing the seal assembly before releasing the slips. The lock ring is designed with asymmetric teeth that allow the seal to be released first, creating space for the seal to expand and relieve pressure before the slips are released. This sequential approach prevents the slips from binding due to residual rubber pressure.
2Strength
If the seal assembly is compressed to set the packer, then the packer is securely positioned, but the force holding it in place is too strong to relieve pressure during release
Solution Approach 1:
The lock ring is segmented into asymmetric teeth that engage with corresponding features on the outer assembly. This segmentation allows selective release of the seal assembly while maintaining engagement of other components. The asymmetric design provides different release characteristics for different segments, enabling controlled pressure relief.
Solution Approach 2:
The patent introduces a radial dimension to the release mechanism. The lock ring teeth are designed to allow radial movement of the seal assembly relative to the outer assembly during release. This radial component of movement creates the necessary space for the seal to expand and relieve pressure, adding a dimensional aspect to the release process.
3Ease of operation
If the mandrel is cut and raised to take the cone away, then space is created for pressure release, but the mechanism becomes more complex
Solution Approach 1:
The patent merges the mandrel cutting function with the lock ring release mechanism. The same axial movement that raises the mandrel to release the cone also allows the lock ring asymmetric teeth to disengage, creating space for pressure release. This combines multiple functions into a single coordinated action, reducing overall system complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution ensures the sealing system is unloaded before slip relaxation, effectively releasing the pressure and preventing binding, with the radial movement of the mandrel and collet heads allowing the sealing element to stretch out and facilitate smooth release of the packer or plug.
Implementation Method 1
the force of the retained rubber pressure to forcibly push the locking member to retract in a radial direction
Implementation Method 2
the residual rubber pressure to force the heads toward the mandrel into the space created
Data Source
AI summary
A retrievable packer has its sealing system unloaded before the slip system is relaxed by separation of slip cones from slips that flank the seal assembly. The mandrel is cut so that the portion above the cut can be raised to take a cone up and away from collet heads which previously were trapped by the cone. The collet heads are disposed between opposed sloping surfaces so that the retraction of the cone from under the heads allows the residual rubber pressure to force the heads toward the mandrel into the space created by relative movement of the mandrel that took the wedge cone uphole. The heads are at ends of fingers having a radially inward bias to further assist retraction of the heads toward the mandrel. With the heads retracted the sealing element stretches out before slip cones are moved relative to the slips.