Expandable Liner Hanger Sealing Mill Scale
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Solution Overview
Problem
Existing liner hangers face issues with loose parts disrupting setting operations, difficulty in retrieval, inability to perform conventional cementing, and ineffective sealing due to pipe scale in the casing string, leading to fluid pressure leaks and compromised sealing and load-supporting capacity.
Innovation Solution
An expandable liner hanger system using a high-strength steel tubular anchor with metal sealing elements and a tubular expander that expands to securely engage with the casing string, providing improved sealing and gripping capabilities without the need for extensive deformation, thus maintaining elasticity and reducing the length of the expandable hanger.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If prior art liner hangers are expanded to provide sufficient frictional force to support the liner weight, then the gripping strength is improved, but the hanger length becomes substantial (10 feet or more) and plastic deformation is required resulting in loss of elasticity
Solution Approach 1:
The tubular expander is nested within the tubular anchor, allowing the expander to be stored in a compact form during installation and then expanded to provide the necessary gripping force. This nesting approach eliminates the need for a long hanger while maintaining sufficient frictional force.
Solution Approach 2:
The invention changes the physical state of the hanger from a permanently plastic-deformed state to an elastically deformable state. The tubular anchor and expander are designed to elastically expand and maintain their expanded diameter, preserving elasticity while providing sufficient gripping force over a shorter length.
2Reliability
If conventional seals are used in the presence of pipe scale, then the device complexity is reduced, but the sealing effectiveness deteriorates due to inability to seal effectively with the interior bore of the casing string
Solution Approach 1:
The sealing approach changes from using elastomeric materials that cannot conform to mill scale to metal-to-metal sealing surfaces that can effectively seal against the scaled interior bore of the casing string, achieving reliable sealing in the presence of pipe scale.
3Force
If the tubular anchor undergoes plastic deformation during expansion, then the expansion force is sufficient to engage the casing string, but the elasticity needed to maintain fully expanded diameter is lost leading to relaxation of gripping strength
Solution Approach 1:
The material behavior is changed from plastic deformation to elastic deformation. The tubular anchor and expander are designed with sufficient elastic capability to undergo the necessary expansion while maintaining their expanded diameter, thereby preserving both the expansion force and the elasticity needed to maintain gripping strength.
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 system achieves effective sealing and load support with shorter hanger lengths, ensuring reliable operation and easy tool release, while maintaining the necessary frictional force to support the liner, even in the presence of mill scale, thereby enhancing the sealing integrity and load-supporting capacity.
Implementation Method 1
The tubular expander remains positioned inside the expanded tubular anchor for support at its final expanded diameter, thus sandwiching the expanded and plastically deformed tubular anchor between the elastically deformed casing string and the elastically deformed tubular expander
Implementation Method 2
The metal sealing elements are superior to elastomeric or other conventional seals because they provide effective sealing notwithstanding the presence of mill scale in the casing string
Data Source
AI summary
A liner hanger seals with casing string 8 having mill scale and supports a liner 98 within a well. The liner hanger includes a tubular anchor 48 and a tubular expander 40. The tubular anchor 48 may be positioned in the casing string 8 using an inner mandrel 10. An actuator assembly 6 forcibly moves the tubular expander 40 into the tubular anchor 48, expanding the tubular anchor 48 to grippingly engage the expanded tubular anchor 48 against the casing string 8 and to form a circumferential seal between metal sealing elements 52 on the tubular anchor 48 and the interior wall of the casing string 8. The metal sealing element 52 is oversized to provide rigidity, heat shrunk onto the tubular anchor 48, and abrasively dressed to remove excess material prior to installation of the liner hanger.