Packoff Nipple Elastomeric Seals Reusable Wellhead
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Solution Overview
Problem
Existing packoff nipples are prone to damage during well tubing or casing entry and exit, particularly when passing restricted internal diameters, and are susceptible to seal failure due to extreme temperatures and misalignment, leading to permanent deformation and increased operational costs.
Innovation Solution
A non-extruding packoff nipple design featuring axially compressible elastomeric sealing rings that expand radially under pressure to seal the annular space, with a mechanism that allows the rings to return to their original shape upon pressure equalization, preventing permanent deformation and enabling safe extraction and reuse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If extruded seals are used in packoff nipples, then sealing capability is improved, but the seals become permanently deformed when actuated and cannot be reused
Solution Approach 1:
Instead of using extruded seals that permanently deform, the patent employs non-extruding elastomeric sealing members that return to their original shape after actuation. The sealing members are axially moveable and compressible, allowing them to be actuated and then returned to their pre-actuated state for reuse.
Solution Approach 2:
The sealing members are designed to be axially moveable and dynamically responsive to pressure differential changes. They can move axially in response to pressure differential changes and return to their original position when pressure is equalized, enabling repeated actuation and de-actuation cycles.
2Reliability
If elastomeric seals are used in packoff nipples, then sealing is achieved, but the seals are susceptible to damage during well tubing entry and exit
Solution Approach 1:
The patent incorporates a protective sleeve that cushions and protects the elastomeric sealing members during entry and exit operations. The sleeve is designed to reduce mechanical damage to the seals when the packoff nipple is inserted into or removed from the well tubing, preventing premature degradation.
Solution Approach 2:
The protective sleeve acts as an intermediary element between the elastomeric sealing members and the well tubing. It provides a cushioning layer that reduces direct mechanical contact and damage to the seals during insertion and extraction operations.
3Reliability
If elastomeric seals are used in packoff nipples, then sealing is achieved, but the seals are damaged by exposure to extreme temperatures
Solution Approach 1:
The patent specifies that the elastomeric sealing members be made from materials with temperature resistance properties appropriate for the well stimulation environment. The sealing members are designed to maintain their elastic properties and sealing capability across the expected temperature range of CO2 and N2 stimulating fluids.
4Ease of operation
If packoff nipple is designed for easy extraction, then operational simplicity is improved, but seal damage risk increases
Solution Approach 1:
The protective sleeve is designed to be removed or retracted before extraction operations, providing cushioning protection to the elastomeric sealing members during the extraction process. This prevents damage to the seals while allowing for relatively simple extraction of the packoff nipple from the well tubing.
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 prevents seal damage and allows for repeated use, reducing operational costs by maintaining the integrity of the sealing rings and avoiding extrusion, thus effectively sealing high-pressure areas without permanent deformation.
Implementation Method 1
an elastomeric sealing member adapted to seal the annular space in response to a pressure differential across the packoff nipple
Implementation Method 2
the elastomeric sealing members are anticipated to collapse to their original shape thereby allowing safe extraction of the wellhead isolation tool
Data Source
AI summary
A packoff nipple for sealing an annular space in a well pipe has a tubular body, a sealing assembly positioned around the tubular body capable of axial movement along the tubular body and a stop to restrain the sealing assembly from extruding in-to the annular space. The sealing assembly includes one or more elastomeric sealing rings having a circumferential groove formed in a downhole face. An axially moveable actuator, such as a packer cup, engages the sealing ring assembly to causes at least a portion of the sealing rings to expand radially outwardly to seal the annular space and cause the sealing ring assembly to contact the uphole stop. The sealing rings are axially compressed between the uphole stop and the actuator to further expand the sealing rings. The uphole stop may be concave to urge the sealing rings away from the well pipe to avoid extrusion or permanent deformation.