Angular Position Sensor Magnetometer Stray Field Correction
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Solution Overview
Problem
Current angular position determination methods in subterranean well drilling operations are limited in accuracy and reliability, particularly in determining the azimuthal orientation of a shaft relative to an outer housing, due to interference from stray or ambient magnetic fields.
Innovation Solution
A well tool equipped with multiple magnetometers positioned in a gas-filled chamber, which sense the magnetic field strength emanating from a rotating magnetic device, allowing for precise determination of the azimuthal position by analyzing sinusoidal curves and correcting for offset values, enabling accurate angular position sensing even in harsh downhole environments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If magnetometers are used to determine angular position in downhole environments, then measurement capability is provided, but measurement precision deteriorates due to interference from stray or ambient magnetic fields
Solution Approach 1:
The patent applies this principle by using the stray magnetic fields not just as interference to be rejected, but by measuring them and using their characteristics (phase and amplitude) to characterize the downhole environment. This environmental characterization is then used to correct the angular position measurements, converting the harmful interference into useful information that improves measurement accuracy.
Solution Approach 2:
The patent implements feedback by continuously monitoring the magnetic field environment, analyzing the stray field characteristics, and using this information to adjust and correct the angular position measurements in real-time. The system feeds back the environmental conditions to the measurement process to compensate for their effects.
2Measurement precision
If multiple magnetometers are positioned in a gas-filled chamber to sense magnetic field strength, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies this principle by designing the magnetometer array system to perform multiple functions: it measures angular position, characterizes the magnetic field environment, determines stray field amplitude and phase, and provides corrections for measurement accuracy. This multi-functionality justifies the increased complexity by delivering comprehensive measurement capabilities.
Solution Approach 2:
The gas-filled chamber acts as an intermediary that protects the magnetometers from direct exposure to harsh downhole conditions while allowing magnetic field sensing. This intermediary structure enables precise measurements without requiring the sensors to withstand extreme temperatures and pressures directly.
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 provides precise and reliable angular position determination of a shaft relative to an outer housing, accounting for stray magnetic fields, and can determine rotational velocity and acceleration, enhancing the accuracy of directional drilling operations.
Implementation Method 1
Each magnetometer senses a magnetic field strength emanating from the magnetic device
Data Source
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AI summary
An angular position sensor can include a magnetic device from which a magnetic field emanates, and multiple magnetometers, whereby each magnetometer senses a varying strength of the magnetic field due to relative rotation between components of a well tool. A method of determining an azimuthal position of a shaft which rotates relative to an outer housing can include securing a selected one of at least one magnetic device and at least one magnetometer to the shaft, securing the other of the magnetic device and the magnetometer to the outer housing, a fluid motor rotating the shaft relative to the outer housing in the well, and the magnetometer sensing a varying strength of a magnetic field emanating from the magnetic device as the shaft rotates relative to the housing.