Gas Lift Latch Collet Locking Against Premature Shearing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing gas lift latches in downhole tools are prone to premature shearing due to dynamic pressure changes, leading to displacement of valves from the mandrel pocket bore, compromising well integrity.
Innovation Solution
The design incorporates a robust dog or collet assembly that replaces the shear pin, with a lock ring and spring mechanism to maintain engagement with the running head, and a collapsible collet to minimize clearance gaps, ensuring secure installation and retrieval of downhole components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shear pin is used to secure the latch, then the latch can be simple in design, but the shear pin is prone to premature shearing under dynamic pressure changes
Solution Approach 1:
The latch body is divided into multiple functional components: a collet assembly with segmented fingers, a lock ring, and a spring mechanism. This segmentation allows each component to perform its specific function - the collet fingers provide radial constriction, the lock ring maintains axial position, and the spring provides continuous engagement force, collectively preventing premature failure while maintaining reasonable design simplicity
Solution Approach 2:
The latch transitions from a static shear pin design to a dynamic system with a collapsible collet assembly that can radially constrict and expand. The spring mechanism enables the latch to dynamically respond to pressure changes and mechanical loads, maintaining reliable engagement under varying downhole conditions while allowing controlled movement during installation and retrieval
2Reliability
If a robust dog or collet assembly with lock ring and spring mechanism is used, then the reliability under mechanical loads and cyclic pressures is improved, but the device complexity increases
Solution Approach 1:
Multiple functions are merged into integrated components: the collet assembly combines radial constriction fingers with a unified body, the lock ring integrates both axial positioning and radial locking functions, and the spring mechanism serves both to maintain engagement force and enable controlled collapse. This merging reduces the number of separate parts while achieving high reliability under mechanical loads and cyclic pressures
Solution Approach 2:
The lock ring serves multiple functions: it maintains axial position of the collet assembly, provides radial locking through engagement with the latch body, and enables controlled release during retrieval. The collet assembly simultaneously provides radial constriction for secure positioning and controlled collapse for retrieval, making the mechanism highly reliable across different operational phases without requiring additional components
3Reliability
If clearance gaps are minimized with collapsible collet, then the secure positioning of downhole components is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The collet assembly changes its radial dimension dynamically - expanded during normal operation to minimize clearance gaps and secure positioning, and collapsed during retrieval to enable removal. This parameter change allows the system to achieve secure positioning without requiring extremely tight manufacturing tolerances, as the adjustable clearance compensates for dimensional variations
Solution Approach 2:
The collapsible nature of the collet assembly allows it to adapt to slight variations in component dimensions by adjusting its radial constrictive force. This dynamic adjustment capability ensures secure positioning across a range of manufacturing tolerances, reducing the stringency of precision requirements while maintaining reliable component positioning
Data Source
AI summary
Latch designs for downhole components are provided. Some latch designs automatically lock in place in a mandrel pocket, for example automatically lock on or relative to both the no-go up and no-go down shoulders of the mandrel, when set. The latch designs reduce the range of movement of the latch within the mandrel pocket.