Casing Mill With Ultra-High Expansion Blade for Nested Casing
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Solution Overview
Problem
Current casing milling technologies in the resource recovery and fluid sequestration industries are inefficient, particularly during plug and abandonment operations, as they struggle to effectively mill nested casings with varying diameters and orientations, leading to suboptimal operational profitability.
Innovation Solution
A casing mill system featuring a first milling configuration with a blade for milling a first casing section and a second ultra-high expansion blade for milling a radially outwardly disposed second casing section, along with a stroking tool to facilitate sequential or simultaneous milling, minimizing rotational torque drag and enabling efficient cutting through both casings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single milling blade is used for conventional casing milling, then the device complexity is low, but the productivity is insufficient when milling nested casings with varying diameters
Solution Approach 1:
The milling device is divided into multiple independent milling configurations (first milling configuration with first blade, second milling configuration with second blade), each capable of milling different casing sections. This segmentation allows simultaneous or sequential milling of nested casings, significantly improving productivity while maintaining manageable complexity through modular design.
Solution Approach 2:
The milling device employs a nested structure where the first milling configuration and second milling configuration are arranged concentrically, with the first blade positioned inside the second blade. This nested arrangement mirrors the nested casing structure being milled, allowing both blades to operate simultaneously on their respective casings without interference, thus enhancing productivity without proportionally increasing device complexity.
2Loss of time
If conventional milling methods are used for nested casings, then the device complexity remains low, but the loss of time increases due to sequential milling requirements
Solution Approach 1:
The stroking tool introduces dynamic movement to the milling system, allowing the milling configurations to move axially relative to each other and to the casings. This dynamic capability enables sequential engagement of different blades with different casing sections, reducing total milling time by eliminating the need for complete tool withdrawals and repositioning, while the controlled dynamic movement keeps the mechanism manageable.
Solution Approach 2:
The stroking tool acts as an intermediary mechanism between the power source and the milling blades, coordinating the movement and engagement of multiple milling configurations. This intermediary component manages the complexity of synchronizing multiple blades with nested casings, reducing overall operation time while maintaining device manageability through centralized control.
3Productivity
If multiple milling configurations are used to mill nested casings simultaneously, then the productivity increases, but the rotational torque drag increases
Solution Approach 1:
Each milling configuration is optimized with blade geometry and positioning tailored to its specific casing section. The first blade is optimized for the inner casing while the second blade is optimized for the outer casing, allowing each to cut efficiently with minimal torque requirement. This localized optimization reduces the total rotational torque drag while maintaining high productivity through simultaneous milling.
Solution Approach 2:
The milling blades are designed to engage only the necessary portion of each casing wall required for the operation, rather than milling the entire circumference simultaneously. This partial engagement reduces the total cutting resistance and rotational torque drag while still achieving the productivity goal of milling nested casings efficiently. The stroking tool enables progressive milling that maintains acceptable torque levels.
Data Source
AI summary
A casing mill including a first milling configuration having a first blade for milling a first casing section, and a second milling configuration having a second blade, the second blade being an ultra-high expansion blade for milling a second casing section. A wellbore system including a borehole in a subsurface formation, two nested casings disposed within the borehole, a string disposed within the casings, a casing mill disposed within or as a part of the string and including a first milling configuration having a first blade for milling a first casing section, and a second milling configuration having a second blade, the second blade being an ultra-high expansion blade for milling a second casing section, the second casing section being radially outwardly disposed of the first casing section, and a stroking tool disposed between the first milling configuration and the second milling configuration.