Downhole Tool Collet Retaining Band Release Mechanism
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Solution Overview
Problem
Existing downhole tool release mechanisms, such as shear pins, are unreliable due to quality control issues and variations in material strength, leading to premature release during downhole operations.
Innovation Solution
A collet with a retaining band is used to engage a mandrel, where the collet remains engaged until an axial force is applied, at which point the shear band ruptures, allowing the collet to disengage and be removed from the downhole tool, ensuring consistent and predictable release.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If shear pins are used to releasably connect downhole tools, then the connection can be released, but the reliability is poor due to quality control issues and material strength variations
Solution Approach 1:
The patent changes the failure mode from shear pin fracture (affected by material strength variations) to controlled band rupture. The retaining band is designed with a specific cross-sectional area and material properties (tensile strength) that allow predictable rupture at a predetermined force, eliminating sensitivity to material strength variations that plague shear pins.
Solution Approach 2:
The patent uses a retaining band that circumferentially encircles the collet, creating a redundant constraint system. The band's continuous circumferential structure provides uniform distribution of holding force, replacing the discrete pin-based system with a distributed constraint that is more reliable and less sensitive to manufacturing variations.
2Reliability
If a retaining band is used to keep the collet engaged, then the tool remains securely connected, but the device complexity increases
Solution Approach 1:
The patent combines the retaining function and the releasing function into a single integrated component - the retaining band. The band serves both to hold the collet engaged during normal operation and to rupture predictably when the predetermined force is applied, eliminating the need for separate retaining and releasing mechanisms.
Solution Approach 2:
The retaining band is designed to automatically rupture at the predetermined force without requiring external activation or control systems. The band's own structural properties (cross-sectional area, material tensile strength) determine the release force, making the system self-regulating and eliminating complex control mechanisms.
3Speed
If the collet fingers are allowed to expand freely, then the release is quick, but premature release may occur during tool setting
Solution Approach 1:
The retaining band applies a preliminary constraining force that prevents premature expansion of the collet fingers during tool setting operations. The band maintains the collet in an engaged state until the predetermined force is reached, at which point the band ruptures and allows immediate, unrestricted expansion for rapid release.
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
The mechanism provides a reliable and consistent method for releasing downhole tools, ensuring they remain in place until the predetermined force is applied, preventing premature release and ensuring proper tool setting and removal.
Implementation Method 1
a retaining band disposed about the collet. The retaining band will keep the collet engaged with the downhole tool until an axially directed force, or pull, of a predetermined amount is applied to the collet. Upon application of the predetermined axially directed force, or releasing force, the collet is released from the mandrel of the downhole tool.
Data Source
AI summary
A downhole tool releasing mechanism which includes a collet for releasably engaging a mandrel of a downhole tool. A retaining band is circumferentially disposed about the fingers of the collet for maintaining engagement of the collet and the mandrel prior to application of a predetermined axially directed force on the releasing mechanism. Upon application of such a force the collet fingers expand, breaking the shear band, the mandrel is released and the downhole tool is disengaged.