Wellbore Stage Tool Redundant Closing Sleeve Design
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Solution Overview
Problem
Conventional wellbore stage tools lack true redundancy in sealing mechanisms, as the secondary closing sleeve's ability to seal is dependent on the primary sleeve's functionality, and debris from drilling can interfere with the sealing process, reducing the effectiveness of the secondary closure.
Innovation Solution
A stage tool design featuring a primary and secondary closing sleeve with independent sealing surfaces and motion paths, where the secondary sleeve can seal without relying on the primary sleeve's operation, and is positioned to avoid debris accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secondary closing sleeve is added to provide backup sealing, then reliability is improved, but the secondary sleeve cannot seal independently because it shares a sealing surface with the primary sleeve and is dependent on the primary sleeve's functionality
Solution Approach 1:
The patent divides the sealing function into two independent segments: the primary closing sleeve (1002) with its own sealing surface, and the secondary closing sleeve (1004) with a separate sealing surface. This segmentation allows each sleeve to seal independently without sharing common sealing surfaces, eliminating the dependency problem while maintaining high sealing reliability.
2Device complexity
If the primary and secondary closing sleeves share a sealing surface, then device complexity is reduced, but the secondary sleeve cannot provide true redundancy because it interferes with the primary sleeve operation and vice versa
Solution Approach 1:
The patent resolves the conflict by transitioning from a shared sealing surface (one-dimensional constraint) to separate sealing surfaces positioned at different locations along the tubular wall (adding spatial dimensionality). The primary closing sleeve seals at one location while the secondary closing sleeve seals at another location, allowing both to operate independently without interference.
3Ease of operation
If the primary closing sleeve is drilled out to enable secondary sleeve operation, then the secondary sleeve can be activated, but debris accumulates between the sleeves and prevents proper sealing
Solution Approach 1:
The patent eliminates the need for drilling out the primary closing sleeve by designing the secondary closing sleeve to seal at a different location that does not require removal of the primary sleeve. This preliminary design decision prevents debris generation from drilling operations, allowing the secondary sleeve to be activated and sealed without harmful debris accumulation.
4Reliability
If the primary closing sleeve shifts down but fails to close the ports, then the secondary sleeve should provide backup sealing, but the overlapping ranges of motion cause interference between the two sleeves
Solution Approach 1:
The patent segments the sealing locations so that the primary closing sleeve operates at one position on the tubular wall while the secondary closing sleeve operates at a different position. This spatial segmentation ensures that when the primary sleeve shifts down to close ports, the secondary sleeve can independently shift to its sealing position without mechanical interference, providing true backup sealing capability.
Data Source
AI summary
A stage tool comprises a body with a tubular wall, defining an outer surface and an inner surface. Fluid ports, such as cement circulation ports, extend through the tubular wall. The stage tool further comprises a primary closing sleeve. The primary closing sleeve may be movable along the outer surface of the tubular wall for closing the ports when the treatment of the wellbore stage ends. A secondary closing sleeve may be movable along the inner surface of the tubular wall for closing the port in case of failure of the primary closing sleeve or for redundancy. The primary closing sleeve may be actuated by an internal member joined to the primary closing sleeve by a crosslink and movable on the inner surface. The internal member and the secondary closing sleeve may move along different surfaces on the internal wall to avoid interference.