Annular Wellbore Milling for Off-Center Valve Obstructions
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Solution Overview
Problem
Existing milling devices struggle to efficiently remove partially obstructing valve materials from wellbores, especially when the target material is not centered, leading to inefficiencies and deflection issues, particularly with wireline deployment due to insufficient torque and force.
Innovation Solution
A milling and catching device system comprising an annular cutter and internal milling device, which includes a central body with a catching mechanism, such as a flexible shaft or flapper arms, to maintain milling trajectory and capture debris, enhancing efficiency and effectiveness in removing wellbore obstructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If milling equipment is deployed on wireline, then the device can access the wellbore for milling operations, but the available force and torque are insufficient to overcome bit deflection when target material is not centered
Solution Approach 1:
The patent introduces a centralized milling system where the annular cutter rotates around a central axis rather than relying on wireline-torsion-based rotation. This dimensional change from linear wireline deployment to rotational central axis milling enables sufficient torque application even when target material is off-center, resolving the force deficiency of wireline deployment
2Adaptability or versatility
If the target material is not present at the central axis of the wellbore, then the valve failure position reflects realistic operational conditions, but the bit becomes deflected away from the target reducing milling efficiency
Solution Approach 1:
The patent employs an asymmetric annular cutter design with cutting elements distributed around the central axis, allowing the cutter to maintain stability and cutting efficiency even when the target material (failed valve) is positioned off-center in the wellbore. The asymmetric material distribution compensates for bit deflection and maintains milling productivity
Solution Approach 2:
The central body acts as an intermediary structure that provides a stable central axis and support framework. This intermediary enables the annular cutter to maintain its position and rotation stability regardless of the target material's position, preventing bit deflection and maintaining milling efficiency
3Loss of substance
If a catching mechanism is added to the milling device, then milling debris can be captured and retrieved, but the device complexity increases
Solution Approach 1:
The patent combines the catching mechanism with the central body structure, integrating debris collection functionality into the existing milling device framework. This merging approach captures milling debris without adding separate complex systems, as the catching mechanism shares structural elements with the central support body
Data Source
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AI summary
A milling system may be used to remove the portions of a failed valve that is blocking the wellbore. When milling a partially open valve obstructing the wellbore, the target material to be removed may not be present at the central axis of the wellbore causing the target material to not fully surround the milling bit, which may cause the bit to be deflected away from the target during milling reducing milling efficiency. The disclosed milling system may be used to mill out and capture the coupon for any downhole obstruction that does not have any material near the center axis of the wellbore. A first embodiment of the milling sytem may be configured to fully mill out material within the wellbore while a second embodiment may be used to mill out material within the wellbore and further catch the milled material or coupon.