Active Torque Sensor for Viscometer
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Solution Overview
Problem
Traditional viscometers and rheometers lack the range and resolution to accurately measure the rheological properties of fluids, especially under downhole conditions, due to limitations in spring stiffness, friction compensation, and buoyancy issues with hollow bobs, which affects the measurement of fluid viscosity and torque in subterranean operations.
Innovation Solution
An active sensor system for torque measurement in a viscometer that uses electronic compensation for friction and inertia, eliminating the need for jewel bearings and hollow bobs, and employs a magnetically coupled shaft with a positional sensor to detect minute angular displacements, enabling sensitive torque measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional spring-based torque measurement is used, then the device structure is simple, but the measurement range and resolution are limited due to spring stiffness constraints
Solution Approach 1:
The patent replaces the traditional mechanical spring-based torque measurement system with an electromagnetic actuation system. A voice coil generator creates electromagnetic force to rotate the bob, and a magnetic torque sensor measures the torque required to hold the bob at a specific position. This substitution eliminates the limitations of spring stiffness while providing both measurement range and resolution benefits.
Solution Approach 2:
The patent introduces a magnetic field as an intermediary between the electromagnetic actuator and the torque sensor. The voice coil generates a magnetic field that interacts with a permanent magnet to produce rotational force, while the magnetic torque sensor detects the magnetic field strength at different positions, enabling precise torque measurement without direct mechanical contact.
2Measurement precision
If hollow bobs are used in traditional viscometers, then the device can measure torque, but buoyancy errors occur in high viscosity fluids
Solution Approach 1:
The patent extracts and eliminates the hollow bob component from the traditional viscometer design. Instead of using a hollow bob that interacts with the fluid, the system uses an electromagnetic field to directly apply torque to a simplified rotor, eliminating the source of buoyancy errors while maintaining measurement capability.
Solution Approach 2:
The patent replaces the mechanical hollow bob system with an electromagnetic field-based system. The voice coil generator creates electromagnetic force to rotate the rotor, eliminating the need for hollow bobs that cause buoyancy errors in high viscosity fluids, thereby improving measurement accuracy.
3Ease of operation
If jewel bearings are used for friction compensation, then the device can reduce friction, but the device becomes delicate and difficult to transport
Solution Approach 1:
The patent replaces the mechanical jewel bearing system with an electromagnetic field-based friction compensation system. The voice coil generator creates electromagnetic force that can compensate for friction without requiring delicate mechanical bearings, making the device more robust and easier to transport while maintaining friction compensation capability.
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
This solution provides accurate and sensitive torque measurements, overcoming the limitations of traditional systems by allowing for low-torque detection and reducing errors, thereby improving the assessment of fluid properties under varying conditions.
Implementation Method 1
inducing the counter torque force by a stator coil on a magnet rotor coupled to the bob
Implementation Method 2
a positional sensor disposed about the shaft, wherein the positional sensor detects rotational position information associated with the bob
Data Source
AI summary
Viscosity assemblies may be used to determine the viscosity of a sample fluid at a surface location under one or more downhole conditions prior to pumping or flowing of the sample fluid downhole. A viscosity assembly may include a bob assembly disposed in a container that includes a bob disposed about a magnet rotor that rotates when a shear force is applied by the flow of the sample fluid in the container. A stator coil may receive a control signal that induces a force or a voltage that causes the magnet rotor to rotate the bob by a predetermined distance to position the bob from the rotated position back to the initial position.