Packer Extension Release via Tubular Cut and Left-Handed Thread
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Solution Overview
Problem
Existing mechanically releasable packer designs face issues with reliance on seal stacks for backup connections, which complicate testing and are prone to leaks under thermal and tensile loads, and require high torque for release, risking string shear and costly retrieval operations.
Innovation Solution
A tubular cut above the metal to metal threaded connection exposes a left-handed square thread for engagement by a release tool, allowing for string removal without rotation, using a cutting tool that preserves the outer sleeve and reduces the risk of damage to the threaded connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a seal stack is used as backup to the metal to metal seal, then reliability is improved, but device complexity increases and testing becomes more complex
Solution Approach 1:
The invention removes the seal stack from the packer extension design, extracting only the metal to metal threaded connection. This eliminates the complexity of having multiple seal components while maintaining reliability through the robust metal-to-metal threading that provides both sealing and mechanical connection functions.
Solution Approach 2:
The metal to metal threaded connection serves multiple functions simultaneously: it provides the mechanical seal, the structural connection, and the release mechanism. This multi-functionality eliminates the need for separate seal stack components while maintaining connection reliability under thermal and tensile loads.
2Ease of operation
If torque is applied to unthread the string from the packer, then release is achieved, but string shear risk increases
Solution Approach 1:
Instead of rotating the string to unthread it (conventional approach), the invention inverts the release mechanism by using a left-handed square thread on the outer sleeve that engages a release tool. This allows the packer to be released by applying upward force without rotating the string, eliminating the torque-induced shear risk while maintaining release capability.
Solution Approach 2:
The invention segments the release function into two independent parts: the original right-handed thread for initial connection and an additional left-handed square thread on the outer sleeve for release. This segmentation allows the release operation to occur without torque application to the main string, preserving string integrity.
3Ease of operation
If a cutting tool is used to sever the string above the thread, then string removal is enabled, but manufacturing complexity increases
Solution Approach 1:
The invention incorporates a pre-designed cut zone with an expanded length of wall during manufacturing. This preliminary preparation creates a predetermined weak point that allows for clean, controlled severing of the string above the threaded connection, enabling easy string removal while the expanded wall design actually simplifies the cutting operation compared to cutting through full-strength tubing.
Data Source
AI summary
A string from the surface is connected to a packer extension with a thread to provide a metal to metal seal for production or injection through the packer. The thread provides a metal to metal seal. The initial string is released from the packer extension by a tubular cut made with a cutting tool above the thread that provides the metal to metal seal to the packer extension. An outer sleeve surrounds an expanded length of wall which is the target cut zone above the threaded connection. A cut through the tubular does not cut the outer sleeve. The outer sleeve features a left handed square thread to engage a known released tool run in on a string to connect to the packer release mechanism and release the packer for removal with the release tool suspended from a string.