Wellbore Safety Joint Time Delayed Secondary Retention
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Solution Overview
Problem
Existing safety joints in wellbores often experience premature actuation due to unintentional shearing of shear pins caused by forces like the firing of perforation guns, leading to inoperability and costly operations to recover stuck tool strings.
Innovation Solution
A safety joint with a time delayed secondary retention mechanism, featuring a primary and secondary set of shear pins, where a time delay is generated between the shearing of the primary retention mechanism and the loading of the secondary retention mechanism, preventing premature actuation by controlling the flow of metering fluid to slow the extension of the mandrel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single retention mechanism is used in the safety joint, then the device complexity is reduced, but the reliability deteriorates due to premature actuation from unintentional shear pin shearing
Solution Approach 1:
The retention mechanism is segmented into a primary retention mechanism (first shear pin assembly) and a secondary retention mechanism (second shear pin assembly). The primary mechanism handles normal operational retention while the secondary mechanism provides backup retention that activates only if the primary mechanism fails due to unintentional shearing. This segmentation allows the system to maintain reliability without excessive complexity by dividing the retention function into specialized subsystems.
2Speed
If the secondary retention mechanism engages immediately after primary mechanism failure, then the response time is reduced, but the harmful effect increases due to premature actuation from perforation gun forces
Solution Approach 1:
The secondary retention mechanism is pre-positioned and pre-loaded but remains inactive during normal operation. The mechanism includes a time delay feature that prevents the secondary shear pin assembly from engaging immediately when the primary mechanism fails. Instead, the secondary mechanism is designed to engage only after a predetermined time delay, ensuring that transient forces from perforation gun firing do not trigger premature actuation. This preliminary positioning with delayed activation allows the system to respond reliably to actual failures while ignoring transient disturbances.
3Reliability
If a time delay mechanism is added to prevent premature actuation, then the reliability is improved, but the device complexity increases
Solution Approach 1:
A time delay mechanism acts as an intermediary between the primary and secondary retention mechanisms. This intermediary component includes a time delay element (such as a friction element, viscous fluid damper, or mechanical delay device) that mediates the transfer of force from the primary mechanism to the secondary mechanism. The time delay mechanism allows transient forces to pass through without triggering the secondary mechanism, while still transmitting sustained forces that indicate actual failure. This intermediary approach adds minimal complexity while significantly improving reliability by filtering out false triggers.
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
Prevents premature actuation of the safety joint, reducing the likelihood of costly operations to recover stuck tool strings by ensuring the secondary retention mechanism engages only after the primary mechanism has been sheared, thereby maintaining the integrity of the tool string deployment.
Implementation Method 1
controlling the flow of metering fluid to slow the extension of the mandrel
Data Source
AI summary
Certain aspects and features of the present invention are directed to a safety joint that can be disposed in a wellbore through a fluid-producing formation. The safety joint can include a body configured to be disposed in the wellbore, a primary retention mechanism, a secondary retention mechanism, and a time delay mechanism. The primary retention mechanism can be coupled to the body and can prevent the actuation of the safety joint. The secondary retention mechanism can be coupled to the body and can prevent the actuation of the safety joint in response to the primary retention mechanism allowing the actuation of the safety joint. The time delay mechanism can generate a time delay between the primary retention mechanism allowing the actuation of the safety joint and the secondary retention mechanism preventing the actuation of the safety joint.