Magnetically Coupled Position Sensor for Well Tool

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Solution Overview

Problem

Existing well tools face challenges in accurately determining the position of closure assemblies, which affects the regulation of fluid flow, due to limitations in position sensors regarding space, reliability, environmental durability, cost, and efficiency.

Innovation Solution

A magnetically coupled position sensor is developed using magnetically permeable materials to increase magnetic flux density between aligned magnet assemblies, allowing for precise displacement measurement and improved magnetic coupling force, enabling accurate determination of relative positions in well tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional position sensors are used in well tools, then the tool can determine closure assembly position, but the sensor fails to provide sufficient accuracy and reliability in hostile downhole environments

Engineering Contradiction:

Improvesensor reliabilityVSAvoidhostile environment effects

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces conventional mechanical position sensors with a magnetically coupled sensing system. Magnets are attached to the closure assembly and stator, with a position sensor on the rotor detecting magnetic field changes to determine angular position. This magnetic coupling eliminates direct mechanical contact, improving reliability in hostile environments while maintaining measurement capability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces magnetic fields as an intermediary between the closure assembly and the position sensing system. The magnets on the closure assembly and stator create a magnetic field that couples the moving and stationary parts, allowing position detection without direct mechanical connection and protecting the sensor from harsh downhole conditions.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If magnet assemblies are used to improve magnetic coupling, then position sensing accuracy improves, but the device complexity increases

Engineering Contradiction:

Improveposition sensing accuracyVSAvoidsensor structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the magnetic coupling system into separate magnet assemblies: one attached to the closure assembly (moving part) and another attached to the stator (stationary part). This segmentation allows the position sensor to be mounted on the rotor rather than the closure assembly, simplifying the overall structure while maintaining measurement precision through magnetic field detection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent inverts the conventional approach by placing the position sensor on the rotor and using magnetic coupling to sense the position of the closure assembly indirectly. Instead of directly measuring closure assembly position with a sensor mounted on it, the system measures the relative angular position between the rotor and stator through magnetic field interaction, reducing structural complexity.

Inventive Principle:

Principle #13The other way round (Inversion)

3Force

If magnetically permeable material is added to increase magnetic flux density, then the magnetic coupling force improves, but the manufacturing complexity increases

Engineering Contradiction:

Improvemagnetic coupling forceVSAvoidmanufacturing simplicity

Core Design Contradiction:

ForceVSEase of manufacture

Solution Approach 1:

The patent applies magnetically permeable material selectively at specific locations where magnetic flux density needs enhancement, such as at the magnet assemblies or in the magnetic circuit path. This localized application improves magnetic coupling force where needed without requiring the entire sensor assembly to be manufactured with special materials, maintaining ease of manufacture for the overall device.

Inventive Principle:

Principle #3Local quality

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 enhances the accuracy and reliability of position sensing in well tools, allowing for precise regulation of fluid flow while withstanding hostile environments and reducing operational costs.

Implementation Method 1

a magnetically permeable material which increases a magnetic flux density between the magnet assemblies

Methodology Applied

Scientific EffectMagnetic flux density enhancement: Magnetic Field

Implementation Method 2

the other magnet assembly being movably attached to the other member and magnetically coupled to the first magnet assembly

Methodology Applied

Scientific EffectMagnetic coupling: Magnetism

Data Source

PatentUS7673683B2Well tool having magnetically coupled position sensor

Publication Date: 2010.03.09 WELLDYNAMICS INC

AI summary

A well tool having a magnetically coupled position sensor. In operation of a well tool, relative displacement is produced between members of the well tool. A magnetically coupled position sensor includes one magnet assembly attached to a member for displacement therewith and another magnet assembly movably attached to the other member and magnetically coupled to the first magnet assembly for displacement therewith. The position sensor further includes a magnetically permeable material which increases a magnetic flux density between the magnet assemblies. In another position sensor, one magnet assembly includes a magnet having a pole axis, the other magnet assembly includes another magnet having another pole axis, and the pole axes are aligned with each other.