Expandable Junk Mill Stabilizer for Reduced Diameter Navigation
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Solution Overview
Problem
Existing borehole milling tools with fixed or pressure-actuated blades face challenges in navigating reduced diameters due to tubular patches, leading to increased milling time and incomplete milling, and are prone to seal failures and jamming issues.
Innovation Solution
A borehole mill design featuring blades that radially extend along an inclined dovetail via weight-setting, with a retainer release and a compressed spring for retraction, and an articulable stabilizer for enhanced stability during milling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If pressure-actuated camming mechanism is used to extend blades radially, then blade extension is achieved, but device complexity and cost increase due to seals and multiple components
Solution Approach 1:
The invention extracts and eliminates the complex pressure-actuated camming mechanism and its associated seals from the system. Instead, it uses a simple gravity-based mechanism where blades extend radially when the mill is lowered into the hole, and a return spring automatically retracts them when the mill is pulled out. This removes unnecessary complexity while maintaining the essential blade extension function.
Solution Approach 2:
The blade extension mechanism becomes self-actuating through gravity. When the mill is lowered, weight automatically pushes the blades radially outward along the dovetail groove without requiring external pressure actuation. The return spring then automatically retracts the blades when the mill is pulled out, creating a self-service system that eliminates complex control mechanisms.
2Ease of operation
If mill diameter is reduced to clear tubular patches, then navigation through reduced diameters is achieved, but milling time increases and complete milling is not achieved
Solution Approach 1:
The mill transitions from a static fixed-diameter design to a dynamic variable-diameter design. The blades can extend radially when needed to clear obstructions like tubular patches, allowing the mill to navigate reduced diameters. Once past the obstruction, the blades can be retracted to minimize diameter and maintain milling efficiency. This dynamic adjustment resolves the contradiction between navigating tight spaces and maintaining productivity.
3Ease of manufacture
If fixed outer dimension blades are used, then manufacturing simplicity is maintained, but utility in applications with tubular patches is limited
Solution Approach 1:
The blade system transitions from a fixed static design to a dynamic adjustable design. Blades can extend radially along dovetail grooves when the mill encounters obstructions like tubular patches, providing the adaptability needed to clear obstacles. When obstructions are passed, the blades can be retracted to minimize diameter. This dynamic capability maintains manufacturing simplicity while dramatically increasing versatility in handling various well conditions.
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 design allows for efficient navigation through reduced diameters with complete milling and reliable blade extension/retraction, reducing costs and complexity while ensuring stable operation.
Implementation Method 1
Setting down weight releases a retainer and energizes a return spring that is held compressed during milling. Picking up the mill allows the spring to reverse the blade movement with respect to the mandrel for retraction of the blades.
Implementation Method 2
Axial displacement of the blades along respective dovetails breaks a shear pin on a follower sleeve that is spring biased off a gage ring on the mandrel
Data Source
AI summary
A stabilizer system articulates at least one blade independently of an extendable blade for a through tubing mill. The stabilizer can be actuated with flow, pressure or set down weight. A piston responds to flow or pressure from the surface and an elongated member can cam out the stabilizer with set down weight on the extendable blades.