Lockdown Sleeve Redundant Sealing Casing Hanger
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Solution Overview
Problem
Existing lockdown sleeves and running tools for securing a casing hanger to a wellhead often lack redundant sealing, which can compromise safety during production operations and well intervention, as they typically rely on a single seal between the wellhead and casing hanger, and may not adequately address axial movement and sealing integrity.
Innovation Solution
A lockdown mechanism and running tool that provide redundant sealing by using a lockdown sleeve to limit axial movement of the casing hanger, with a first seal between the sleeve and the wellhead and a second seal between the seal sleeve and the casing hanger, ensuring enhanced sealing integrity through a redundant seal configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single seal is used between the wellhead and casing hanger, then the device complexity is reduced, but the reliability of sealing is compromised
Solution Approach 1:
The sealing system is divided into multiple independent seals: a primary seal between the wellhead and casing hanger, and a secondary seal between the lockdown sleeve and casing hanger. This segmentation provides redundant sealing paths, ensuring that if one seal fails, the other maintains sealing integrity, thereby resolving the contradiction between reliability and complexity.
Solution Approach 2:
The patent incorporates a secondary seal as a preventive measure before seal failure can compromise the system. This redundant seal acts as a backup barrier that prevents harmful effects (leakage) even if the primary seal degrades or fails during operation, applying the beforehand cushioning principle to enhance reliability.
2Reliability
If no seal is provided by the lockdown sleeve, then the device complexity is reduced, but the sealing integrity of the annulus is compromised
Solution Approach 1:
The lockdown sleeve is designed to perform multiple functions: it provides axial positioning of the casing hanger and simultaneously incorporates a secondary seal to provide redundant annulus sealing. This multi-functionality resolves the contradiction by integrating sealing capability into the lockdown sleeve without requiring a separate sealing device, thus maintaining reliability while controlling complexity.
3Stability of the object's composition
If axial movement of the casing hanger is not limited, then the ease of operation is improved, but the stability of the casing hanger position is compromised
Solution Approach 1:
The lockdown sleeve is pre-positioned within the wellhead before the casing hanger is installed. During installation, the casing hanger is simply lowered into place where it automatically engages with the pre-positioned lockdown sleeve, which then limits axial movement. This preliminary action resolves the contradiction by enabling easy installation without requiring complex positioning mechanisms, while simultaneously ensuring position stability through the engagement mechanism.
Data Source
AI summary
The lockdown mechanism (10) and running tool (50) are provided for securing the casing hanger (12, 13) within the wellhead (14) and sealing the annulus between the casing and the wellhead. The lockdown ring (20) fixes the lockdown sleeve (40) to a wellhead in response to a lockdown piston (22). A first seal (24) energized by the running tool seals between the lockdown sleeve and the wellhead. Ball seat (30) is axially movable within the running tool, and a second seal also energized by the running tool (32) seals between the lockdown sleeve and the casing hanger.