Axial Magnetometer Compensation for Downhole Magnetic Interference
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Solution Overview
Problem
Conventional drilling operations face challenges in accurately determining wellbore inclination and azimuth due to intermittent magnetic interference from sources like solenoid actuated valves and electromagnetic transmitters, which affect magnetometer measurements.
Innovation Solution
Compensate for electromagnetic interference by computing averages of magnetic field measurements during interference-free and interference periods, calculating an offset, and applying it to subsequent measurements to correct for interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If magnetometer measurements are made continuously during drilling operations, then wellbore azimuth can be determined at discrete points, but intermittent electromagnetic interference from solenoid valves and EM transmitters causes significant errors in the measurements
Solution Approach 1:
The system performs preliminary actions by computing averages during known interference-free intervals before the interference occurs, establishing a baseline magnetic field value. This preliminary baseline is then used to compensate for measurements taken during subsequent interference periods, allowing continuous measurements to be corrected using pre-established reference data.
Solution Approach 2:
The system implements feedback by continuously monitoring the magnetic field measurements, detecting when interference occurs, and using the computed interference-free averages to generate corrected measurements. The compensation process creates a feedback loop where past interference-free measurements inform the correction of current interference-affected measurements, enabling continuous accurate azimuth determination despite intermittent interference.
2Extent of automation
If automated drilling routines use magnetometer measurements for steering, then drilling direction can be controlled along a desired path, but susceptibility to magnetic interference from tool components creates significant errors
Solution Approach 1:
The system establishes a preliminary baseline of the magnetic field during interference-free intervals by computing averages. This pre-established baseline is stored and readily available when interference occurs, allowing the automated steering system to quickly compensate for interference without interrupting the automated drilling routine, thus maintaining both automation and reliability.
Solution Approach 2:
The compensation mechanism provides continuous feedback to the automated steering system by correcting magnetometer readings in real-time. When interference is detected, the system uses the pre-computed averages to generate corrected measurements, ensuring that the automated steering routine receives reliable data even in the presence of magnetic interference from solenoid valves and EM transmitters.
3Loss of information
If EM transmitters are deployed near the drill bit for deep reading resistivity measurements, then formation characterization is improved, but magnetic interference with magnetometer measurements increases
Solution Approach 1:
The system extracts and separates the interference component from the total magnetic field measurements. By computing averages during interference-free intervals and comparing them with measurements taken during EM transmitter operation, the system isolates the interference portion and removes it from the corrected measurements, allowing both EM transmitter functionality and magnetometer accuracy to coexist.
Solution Approach 2:
The computed average from interference-free intervals serves as an intermediary reference value. This intermediary baseline mediates between the interfering EM transmitter signals and the magnetometer measurements, allowing the system to compensate for interference and maintain accurate azimuth measurements even when EM transmitters are actively characterizing the formation.
4Loss of information
If solenoid actuated valves are used in mud pulse telemetry, then data transmission capability is provided, but magnetic interference causes significant errors in wellbore azimuth measurements
Solution Approach 1:
The system performs preliminary measurements and computes averages during intervals when the solenoid valves are inactive and no telemetry is occurring. This preliminary baseline is established before the next telemetry cycle begins, allowing the system to compensate for the known interference patterns associated with solenoid operation while maintaining data transmission capability.
Solution Approach 2:
The system implements feedback by monitoring the operational state of the solenoid valves and using the pre-computed averages to correct magnetometer measurements during telemetry cycles. The compensation feedback ensures that azimuth measurements remain accurate even when solenoid actuated valves are actively transmitting data to the surface.
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
Improves the accuracy of wellbore azimuth measurements, enabling precise automated steering in drilling operations by effectively mitigating the effects of intermittent magnetic interference.
Implementation Method 1
making axial magnetic field measurements in a downhole tool deployed in the wellbore
Implementation Method 2
Wellbore inclination is commonly derived (computed) from tri-axial accelerometer measurements of the earth's gravitational field
Data Source
AI summary
A method for making axial magnetic field measurements in a downhole tool includes evaluating axial magnetic field measurements to determine a magnetic interference offset and removing the magnetic interference offset to obtain compensated axial magnetic field measurements.