Collet Lock Assembly for Downhole Load Diversion
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Solution Overview
Problem
Conventional downhole assemblies face challenges in isolating axial loads from components and managing bi-directional movement and load transfer, as existing devices only allow one-directional free movement and load transfer, and cannot be released once engaged.
Innovation Solution
A collet lock assembly that can switch between 'RELEASE' and 'SET' positions, allowing bi-directional movement when disengaged and bi-directional load transfer when engaged, by using a shear screw and spring mechanism to engage and disengage collet fingers with the mandrel, thereby diverting axial loads away from components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If body lock rings or internal slips are used to control axial load paths, then load diversion in one direction is achieved, but bi-directional load transfer and release capability are lost
Solution Approach 1:
The collet lock assembly employs a dynamic locking mechanism where collet fingers can transition between engaged and disengaged states. The assembly housing moves axially to engage or disengage the collet fingers from the mandrel, enabling the system to switch between locked and released states. This dynamic capability allows bi-directional load transfer when engaged and free bi-directional movement when disengaged, resolving the contradiction between load transfer capability and release capability.
2Force
If conventional lock mechanisms are engaged to prevent mandrel movement, then load transfer is achieved, but bi-directional movement capability is lost
Solution Approach 1:
The mechanism allows the collet lock assembly to dynamically switch between two operational states: when engaged, the collet fingers grip the mandrel to transfer axial loads bi-directionally; when disengaged, the assembly housing moves axially to release the collet fingers, restoring bi-directional movement capability. This dynamic state switching resolves the contradiction between load transfer and movement capability.
3Reliability
If axial loads are directed through packer elements to activate them, then packer function is achieved, but mandrel crushing and bursting risks increase
Solution Approach 1:
The collet lock assembly extracts the axial load path from the mandrel and packer elements by providing an alternative load transfer path through the collet fingers gripping the mandrel. When engaged, the collet lock assembly carries the axial loads directly to the slip assembly, bypassing the packer elements. This extraction of the load path eliminates the harmful effect of axial loads increasing mandrel crushing and bursting risks while maintaining packer activation capability.
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
Enables repeated cycling between 'RELEASE' and 'SET' positions, reducing radial compressive loads on the mandrel and allowing axial loads to be isolated from tool components, thus reducing the risk of mandrel damage and improving operational flexibility.
Implementation Method 1
a spring positioned between the assembly housing and the shear ring such that the shear ring is biased away from the assembly housing by the spring
Implementation Method 2
a shear screw positioned along the assembly housing and a shear ring positioned between the assembly housing and the mandrel, the shear screw being coupled to the shear ring
Data Source
AI summary
A collet lock assembly for use on a downhole tool allows repeat cycling of a “RELEASE” and “SET” position. In the “RELEASE” position, the collet lock assembly allows bi-directional relative movement of the mandrel in relation to the collet lock assembly, while in the “SET” position, the assembly allows bi-directional load transfer along the mandrel directly into the slip assembly while diverting axial loads away from components positioned along the downhole tool.