Packoff Seal Segmented Deformable Elements
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Solution Overview
Problem
Conventional packoff seals used in oil and gas well servicing operations deteriorate due to heat and vibration, leading to frequent replacements and inadequate sealing performance.
Innovation Solution
A packoff seal design featuring multiple deformable elements and inserts, where the deformable elements have a lower compressive strength than the inserts, forming multiple seals around a cable when subjected to longitudinal or radially inward forces, and a bellows can apply a radially inward force to enhance sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional packoff seals use a single piece of rubber molded into a cylindrical shape, then the structure is simple and easy to manufacture, but the seal deteriorates due to heat and vibration leading to frequent replacement
Solution Approach 1:
The packoff seal is divided into multiple segments including a body, multiple deformable elements, and multiple inserts. This segmentation allows each component to perform specific functions: the body provides structural support while the deformable elements create sealing contact with the cable. The segmented design improves reliability by distributing stress and reducing heat generation compared to a single monolithic rubber piece.
Solution Approach 2:
The packoff seal uses composite construction combining deformable elements made of elastomeric material with inserts made of metal or other rigid materials. This composite approach allows the deformable elements to provide sealing contact while the inserts provide structural support and resistance to heat and vibration, thereby improving overall durability and resistance to deterioration.
2Reliability
If multiple deformable elements and inserts are used to improve sealing performance, then resistance to deterioration improves, but manufacturing complexity increases
Solution Approach 1:
The seal is segmented into modular components (body, deformable elements, inserts) that can be manufactured separately and assembled. This modular segmentation enables specialized manufacturing processes for each component type while simplifying quality control and replacement procedures.
Solution Approach 2:
The inserts are positioned within the body structure, and deformable elements are nested between the inserts and the cable. This nested arrangement allows compact packaging during manufacturing and assembly, reducing the complexity of handling multiple separate components.
3Reliability
If deformable elements have lower compressive strength than inserts, then the deformable elements can effectively seal around the cable, but the overall structural strength may be reduced
Solution Approach 1:
Different parts of the packoff seal have different mechanical properties optimized for their specific functions. The deformable elements have lower compressive strength to enable effective sealing contact with the cable, while the inserts have higher strength to provide structural support. This local differentiation of material properties ensures both sealing effectiveness and overall structural integrity.
Solution Approach 2:
The combination of softer deformable elements with harder inserts creates a composite structure where each material contributes its optimal properties. The deformable elements conform to and seal around the cable, while the inserts reinforce the structure to maintain overall strength despite the presence of softer sealing elements.
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
The design provides improved resistance to deterioration, maintains effective sealing under varying conditions, and extends the lifespan of the packoff seal by distributing force effectively and reducing contact friction.
Implementation Method 1
A force can be applied to the packoff seal to compress at least three deformable elements in the packoff seal against the cable
Implementation Method 2
the first deformable element, the second deformable element, and the third deformable element can deform in response to the longitudinal force to form three separate seals around a cable disposed within the bore
Implementation Method 3
a bellows can be disposed about the packoff seal and can apply a force radially inward to the packoff seal
Data Source
AI summary
Packoff seals and processes for using same. In some examples, the packoff seal can include a first end cap and a second end cap, a first insert and a second insert, a first deformable element disposed between the first end cap and the first insert, a second deformable element disposed between the second insert and the second end cap, and a third deformable element disposed between the first insert and the second insert. The first end cap, the first deformable element, the first insert, the third deformable element, the second insert, the second deformable element, and the second end cap together can form a body having a bore extending therethrough. The first deformable element, the second deformable element, and the third deformable element can have a compressive strength that is less than a compressive strength of the first and second inserts.