Metal Seal Assembly for Adjustable Casing Sub Sealing
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Solution Overview
Problem
Existing sealing solutions in adjustable casing subs for offshore oil and gas production struggle with effective sealing under varying thermal and mechanical conditions, such as thermal expansion and vibration, often relying on elastomers which may not provide reliable long-term performance.
Innovation Solution
A metal seal assembly with a ductile metal face and resilient cantilevered members, featuring a transition from a clearance to a sealing engagement, utilizing ductile metal inlays for lubricity and elastic deformation to ensure a durable, lubricating, and compressive sealing contact without the need for elastomers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If elastomers are used for sealing in adjustable casing subs, then sealing capability is provided, but reliability under varying thermal and mechanical conditions deteriorates
Solution Approach 1:
The patent transitions from elastomeric sealing to metal sealing, changing the material parameter from polymer to metal. The metal seal face (e.g., stainless steel, Inconel) with specific surface finish (Ra ≤ 32 μin) and the resilient backing material (e.g., phosphor bronze, Inconel X-750) are selected to maintain sealing capability across wide temperature ranges (-50°F to 300°F) and mechanical conditions, eliminating the temperature sensitivity of elastomers.
Solution Approach 2:
The seal assembly uses a composite structure combining a resilient backing material (phosphor bronze, Inconel X-750, or other alloy) with a metal seal face (stainless steel, Inconel, or other alloy). This composite design provides both the elastic deformation capability of the resilient material and the thermal stability and lubricity of the metal face, achieving reliable sealing under varying thermal and mechanical conditions.
2Duration of action of stationary object
If metal seal with interfering diameter is used, then sealing durability is improved, but radial deformation of seal increases
Solution Approach 1:
The patent specifies precise parameter ranges: the interfering diameter is controlled at 0.0005 to 0.002 inches, and the seal face surface finish is maintained at Ra ≤ 32 μin. The resilient backing material's modulus of elasticity is selected (e.g., phosphor bronze with E ≈ 17,000,000 psi, Inconel X-750 with E ≈ 28,000,000 psi) to balance deformation and sealing force, ensuring durability while controlling radial deformation.
Solution Approach 2:
The seal is designed to dynamically adapt its shape during operation. The resilient backing material allows the seal to deform radially when the interfering diameter contacts the seal surface, creating sealing contact. The dynamic deformation is controlled by the material's elastic properties and the precise interfering diameter dimension, enabling the seal to maintain contact under varying loads while returning to its original shape when unloaded.
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 metal seal assembly provides a reliable, durable, and lubricating sealing solution capable of withstanding significant compressive loads, ensuring effective sealing across a wide range of conditions, including thermal expansion and mechanical stress, without the limitations of elastomers.
Implementation Method 1
The seal may have a metal face, the face having an interfering diameter with the seal surface causing radial deformation of the seal as it moves axially within the annulus
Implementation Method 2
utilizing ductile metal inlays for lubricity and elastic deformation to ensure a durable, lubricating, and compressive sealing contact
Implementation Method 3
a resilient cantilevered member having a sealing surface on its free end that engages the other side of the housing
Implementation Method 4
The compressive sealing surface may be a spring like element
Data Source
AI summary
An adjustable casing sub having an outer housing, an inner housing insertable into the outer housing, and a ratcheting system for coupling the inner housing within the outer housing. An annulus is between a portion of the inner and outer housing, the annulus including an inwardly tapered section. A metal faced seal is disposed in the annulus, wherein the metal faced seal includes a sliding surface and a compressive sealing surface. The sliding surface may include a malleable inlay and the compressive sealing surface may include a spring like element. Moreover, the metal faced seal radial thickness is greater than the inwardly tapered section radial thickness.