Drillable Latching Plug Retention Fins Milling
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Solution Overview
Problem
Conventional methods for securing and removing downhole tools in wellbores face challenges in reliable engagement and efficient milling, leading to potential damage to drill bits and increased vibrations during the process.
Innovation Solution
The use of latching dogs with engagement arms and retention fins, made from drillable materials, that can be moved radially to engage with the casing and remain engaged during milling, allowing for secure positioning and efficient removal of downhole tools by minimizing damage and vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional latching dogs are used to engage with casing, then secure positioning of downhole tools is achieved, but damage to drill bits and vibrations increase during milling removal
Solution Approach 1:
The latching dog is segmented into multiple functional components: engagement arms for securing to the casing, retention fins for maintaining engagement during milling, and drillable material sections that can be efficiently removed. This segmentation allows each component to perform its specific function optimally while minimizing overall harm during removal.
Solution Approach 2:
Different portions of the latching dog have different material properties and geometries tailored to their specific functions. The engagement arms have hardened surfaces for reliable casing engagement, while the retention fins are designed with drillable materials for easy removal. This local differentiation resolves the contradiction by optimizing each region for its specific role.
2Reliability
If latching dogs with retention fins are used during milling, then engagement is maintained, but the complexity of the latching dog structure increases
Solution Approach 1:
The retention fins are merged with the engagement arms as integral components of the latching dog structure. This integration maintains engagement reliability during milling while avoiding the complexity of separate retention mechanisms. The fins extend from the engagement arms, combining securing and retention functions in a unified structure.
Solution Approach 2:
The engagement arms serve multiple functions: they engage with the casing to secure the downhole tool, and they support the retention fins that maintain engagement during milling. This multi-functionality reduces overall structural complexity while achieving reliable engagement maintenance throughout the milling process.
3Productivity
If drillable materials are used for latching dogs, then milling efficiency is improved, but the strength and durability during engagement may be reduced
Solution Approach 1:
The latching dog incorporates drillable materials in specific regions (retention fins and portions of engagement arms) where ease of removal is critical, while maintaining sufficient strength in engagement-critical areas. This local material optimization achieves both milling efficiency and engagement strength.
Solution Approach 2:
The latching dog may incorporate composite material structures combining drillable materials with harder, more durable materials in strategic locations. This composite approach allows the structure to be both strong during engagement and easily milled during removal, resolving the contradiction between productivity and strength.
Data Source
AI summary
A latching dog includes a dog body, at least one engagement arm protrudes from an outer radial surface of the dog body in a transverse direction, and at least one retention fin protrudes from the dog body in a longitudinal direction. The at least one retention fin maintains the latching dog engaged with a housing surface to keep the latching dog at a desired axial and/or rotational position while milling the housing and latching dog.