Dual-String Milling Tool with Hydraulic Cutting and Reaming
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Solution Overview
Problem
Milling dual outer casing strings in wellbores is time-consuming and expensive due to the need for separate operations and prone to blade failure, especially with larger diameter blades that face increased shear and torsional loads, and are difficult to collapse into the tool body.
Innovation Solution
A dual string section mill with extendable cutting and reaming blocks that are activated by circulating drilling fluid, allowing simultaneous extension of cutting and reaming functions, reducing the need for multiple operations and enhancing blade durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If larger diameter milling blades are used to mill dual outer casing strings, then the cutting capability is improved, but the blades are subject to increased shear and torsional loads leading to blade failure
Solution Approach 1:
The milling operation is segmented into two independent functions: cutting (performed by knife arms) and reaming/cleaning (performed by reaming blocks). This segmentation allows each component to be optimized for its specific function, with reaming blocks providing additional support to reduce torsional loads on the cutting blades.
Solution Approach 2:
The invention changes the operational parameters by using extendable reaming blocks that can be deployed to provide additional support during milling. This parameter change (adding support structure) reduces the torsional and shear loads on the cutting blades, improving their reliability under high-stress conditions.
2Strength
If larger diameter milling blades are used to mill dual outer casing strings, then the cutting capability is improved, but the blades are difficult to collapse into the tool body
Solution Approach 1:
The reaming blocks are designed to be extendable and retractable, transitioning between a compact retracted state for tool body collapse and an extended state for milling operations. This dynamic configuration allows the tool to maintain compactness while providing larger diameter cutting capability when needed.
3Device complexity
If separate operations are used to mill dual outer casing strings, then the milling function is simplified, but the operation becomes time consuming and expensive
Solution Approach 1:
The invention merges the cutting function (knife arms) and the reaming/cleaning function (reaming blocks) into a single dual string section mill tool. This allows both operations to be performed simultaneously in one deployment, eliminating the need for separate milling and window cleanout operations, thereby improving productivity and reducing operational time and cost.
Solution Approach 2:
The tool is designed with multi-functionality, where the same tool body houses both cutting members and reaming blocks that can operate independently or together. This universal design allows the single tool to perform multiple functions (cutting outer casing, cleaning windows, removing debris) that previously required separate specialized tools.
4Reliability
If separate inner string window clean out operation is performed, then the cement layer removal is ensured, but the operation becomes more time consuming
Solution Approach 1:
The reaming blocks are integrated into the same tool as the cutting members, allowing the window cleanout function to be performed simultaneously with the cutting operation. The reaming blocks clean the window and remove cement/debris while the knife arms cut the casing, eliminating the need for a subsequent separate cleanout operation.
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
The solution enables efficient and cost-effective milling of dual outer casing strings by minimizing blade failure and operational complexity, while distributing torsional stresses effectively.
Implementation Method 1
movement of the piston head moves the wedge rod relative to the knife ramp support block by applying a force on the wedge rod by a hydraulic force
Implementation Method 2
the cutting member and the reaming block are configured to extend from the tool body by circulating drilling fluid through the milling tool
Data Source
AI summary
A milling tool for cutting an outer casing string of a wellbore, the milling tool comprising a tool body, an extendable cutting member located in the tool body configured to cut the outer casing string, and an extendable reaming block located in the tool body configured to clean a window formed in an inner casing string of the wellbore, wherein the reaming block is configured to extend from the tool body independently from the cutting member, and wherein the cutting member and the reaming block are configured to extend from the tool body by circulating drilling fluid through the milling tool.