Two-Stage Torque Release Sub for Controlled Downhole Separation
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Solution Overview
Problem
Existing release subs in downhole tubular strings require less torque to break, increasing the risk of the lower portion being left in the well during jarring, and can lead to mechanical issues or damage if the connection breaks.
Innovation Solution
A decoupling apparatus with a torque ring that provides torsional resistance, using shearable elements and retaining devices to control the separation of tubular string sections, ensuring the lower portion remains connected until intended, and allowing retrieval of the upper portion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a release sub is used to provide controlled separation capability, then the ability to separate the string at a predetermined location is improved, but the risk of unintended release during jarring increases
Solution Approach 1:
The release sub incorporates a torque ring with shearable elements that provide dynamic, multi-stage torque resistance. The first torque resistance (from thread engagement) prevents premature release during normal operations and jarring, while the second torque resistance (from shearable elements) provides controlled release capability when intentionally activated, resolving the contradiction between reliability and adaptability
Solution Approach 2:
The release mechanism is segmented into multiple functional components: thread engagement for first torque resistance and shearable elements for second torque resistance. This segmentation allows each component to perform its specific function optimally - the threads provide initial torque resistance to prevent unintended release, while the shearable elements provide the controlled separation capability when needed
2Ease of operation
If jarring is applied to free a stuck tubular string, then the likelihood of freeing the stuck portion is improved, but the risk of causing threaded connections to break increases
Solution Approach 1:
The release sub acts as a predetermined weak point or cushioning element designed to fail safely under excessive torque conditions. By providing a controlled failure mode through the shearable elements, it prevents the propagation of harmful forces that would otherwise cause catastrophic connection breakage in the main tubular string, thus protecting the system while still allowing the jarring operation to proceed
3Ease of operation
If the release sub is designed to require less torque to break, then the ease of controlled separation is improved, but the likelihood of release during normal operations increases
Solution Approach 1:
The torque resistance is dynamic and progresses through two distinct stages: first, thread engagement provides high torque resistance to prevent premature release during normal operations; second, when the shearable elements fail, a controlled release occurs. This dynamic progression resolves the contradiction by providing both high reliability during operation and ease of separation when needed
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 unintended detachment of the lower string portion during jarring, reducing mechanical issues and facilitating safe retrieval of the upper portion by controlling the decoupling process.
Implementation Method 1
the torque ring of the decoupling apparatus provides a necessary torsional resistance to prevent the lower portion of the string from detaching from the upper portion of the string when jarring occurs
Implementation Method 2
The torque ring is rotationally restrained to the top sub section via one or more shearable elements
Data Source
AI summary
A decoupling apparatus for use in a wellbore includes a top sub section and a bottom sub section rotationally coupled to the top sub section. The bottom and top sub sections are aligned along a decoupling apparatus axis. A torque ring is disposed between the top sub section and the bottom sub section. A method for decoupling a lower tubular section from an upper tubular section of a stuck downhole tubular string including the decoupling apparatus includes identifying the stuck downhole tubular string. A first torque is applied to an upper tubular section to rotate a top sub section from a first configuration to a second configuration. A second torque is applied to the upper tubular section to rotate the top sub section from the second configuration to a third configuration in which the top and bottom sub sections are decoupled from one another.