Opposing Thread Safety Joint for Stuck Tool Recovery
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Solution Overview
Problem
Downhole safety joints used in well operations often become stuck, preventing the retrieval of test strings and requiring complex release mechanisms that can be prone to accidental disengagement or equipment damage.
Innovation Solution
A safety joint design featuring opposing threads that are sequentially disengaged through specific rotational and longitudinal movements, eliminating the need for matched machined parts or shearing devices, and providing a simplified process for quick release and recovery, with a focus on reducing the likelihood of accidental release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex release mechanisms (overpull, crushable elements, J-slots) are used to ensure reliable release, then the reliability of release is improved, but the device complexity increases
Solution Approach 1:
The safety joint is divided into two distinct thread sets (first and second opposing threads) with different orientations, allowing sequential disengagement. This segmentation enables a simpler overall design compared to complex mechanisms like J-slots or crushable elements, while maintaining reliable release through the staged thread disengagement process.
2Reliability
If matched machined parts or shearing devices are used for release, then the release mechanism is more reliable, but the ease of manufacture decreases
Solution Approach 1:
Instead of using matched machined parts that require precise matching or shearing devices that cut through components, the invention uses opposing threads that naturally disengage through rotational movement. This inverted approach simplifies manufacturing by eliminating the need for complex matched parts or shearing operations, while maintaining reliable release functionality.
3Reliability
If multiple thread sets with different orientations are used for sequential disengagement, then the likelihood of accidental release is reduced, but the ease of operation increases in complexity
Solution Approach 1:
The first and second thread sets have different orientations (e.g., one right-hand thread and one left-hand thread), creating an asymmetric configuration. This asymmetry prevents accidental release because the specific rotational sequence required to disengage both threads cannot be triggered by random movements. The asymmetric design maintains operational simplicity while significantly reducing accidental disengagement risks.
Data Source
AI summary
Embodiments may generally take the form of a safety joint and methods related thereto. One embodiment may take the form of a safety joint deployable in a well. The safety joint includes a first sub and a second sub coupled to the first sub. The coupling of the two subs may include a first set of threads having a first orientation and a second set of threads having a second orientation different from the first set of threads. The first sub is decoupleable from the second sub upon disengagement of the first set of threads by rotation in a first direction followed by disengagement of the second set of threads by rotation in a direction opposite from the first direction.