Fail-as-is Actuation Mechanism for Downhole Valve Control
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Solution Overview
Problem
Inline barrier valves in downhole well applications are prone to accidental or inadvertent closing or opening, leading to catastrophic failures and risks of equipment damage or personnel injury due to failures in control mechanisms.
Innovation Solution
A failsafe actuation mechanism is introduced that includes a shiftable actuation member with a fail-as-is functionality, where the actuation member can only move the adjustable member a limited number of times before subsequent shifts do not result in movement, ensuring the valve remains in its current operational position, preventing inadvertent actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional actuation mechanism is used for downhole valves, then the valve can be actuated freely to change operational positions, but the valve is susceptible to accidental or inadvertent closing or opening leading to catastrophic failures
Solution Approach 1:
The actuation mechanism transitions from a static direct-coupling state to a dynamic decoupled state after the required number of actuations. The linkage between the actuator and adjustable member is temporarily disengaged, allowing the system to adapt its coupling state based on operational history, thereby preventing inadvertent actuation while maintaining operational flexibility.
Solution Approach 2:
The mechanism pre-counts the number of actuations required to achieve the desired positional change. Before allowing the final actuation that changes the valve position, the mechanism ensures the predetermined number of actuations has been completed, preventing accidental activation with fewer actuations.
2Device complexity
If the actuation member is directly coupled to the adjustable member, then actuation is simple and direct, but any unintended movement of the actuation member directly moves the adjustable member causing potential failures
Solution Approach 1:
A counting mechanism serves as an intermediary between the actuation member and the adjustable member. This intermediary component monitors and controls the transmission of motion, allowing actuation only after the predetermined number of actuations. The intermediary adds complexity but provides the necessary protection against inadvertent actuation.
Solution Approach 2:
The actuation process is segmented into multiple discrete steps rather than a single direct action. The mechanism divides the actuation sequence into predetermined number of individual actuations, with the adjustable member only responding after the complete sequence is executed, thereby reducing the risk of accidental single-action activation.
Data Source
AI summary
A technique enables failsafe control over actuators used to actuate downhole tools. The technique may utilize a well system having a tool with an adjustable member. An actuation mechanism serves as a fail-as-is mechanism and works in cooperation with the adjustable member. The actuation member is shiftable upon receiving a predetermined input; however the actuation member does not move the adjustable member upon each shift. Once the actuation member has been shifted the requisite number of times to move the adjustable member to another position, at least one subsequent shift of the actuation member is not able to cause movement of the adjustable member. The result is a fail-as-is technique for ensuring the tool is not inadvertently actuated to another operational position.