Rotating Magnet Ranging for Pre-existing Well Distance
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Solution Overview
Problem
Current methods for determining the distance to a pre-existing wellbore during drilling operations are inaccurate due to interference from the Earth's magnetic field and require access to the existing well, which complicates precise control of drilling trajectories, especially in emergency situations like blowouts or secondary recovery operations.
Innovation Solution
A method and apparatus that produce a time-varying magnetic field in the second borehole to induce magnetization in the pre-existing well's casing, using a rotating magnet and coil to estimate distance, while filtering out Earth's magnetic field effects and utilizing additional signals for inclination measurements, allowing for precise control of drilling trajectory without direct access to the pre-existing well.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If passive magnetic ranging techniques are used to determine distance to pre-existing wellbore, then access to the pre-existing well is not required, but measurement accuracy is limited due to interference from Earth's magnetic field and residual magnetism
Solution Approach 1:
The patent applies periodic action by using a rotating magnet that generates a time-varying magnetic field at a known frequency. This periodic magnetic field induces a measurable signal in the magnetic casing of the pre-existing wellbore. The periodic nature of the signal allows for precise distance measurement through frequency analysis, while the rotation mechanism enables the field to vary systematically over time, creating a detectable pattern that overcomes the interference from Earth's constant magnetic field.
Solution Approach 2:
The patent replaces traditional mechanical measurement systems with an electromagnetic field-based system. Instead of using mechanical sensors or direct physical access to the pre-existing wellbore, the invention uses a rotating magnet to generate a magnetic field that interacts with the magnetic casing. This substitution eliminates the need for mechanical access while providing sufficient measurement precision through electromagnetic induction principles.
2Measurement precision
If active ranging techniques are used to determine distance to pre-existing wellbore, then measurement accuracy can be good, but access to the pre-existing well is required which complicates drilling operations
Solution Approach 1:
The patent introduces an intermediary element - the magnetic casing of the pre-existing wellbore - that mediates the interaction between the rotating magnet and the measurement system. The magnetic casing acts as a passive mediator that converts the magnetic field generated by the rotating magnet into a measurable electrical signal through electromagnetic induction. This intermediary approach eliminates the need for direct access to the wellbore interior while maintaining measurement accuracy.
3Manufacturing precision
If drilling trajectory control is improved to achieve precise parallel or intersecting boreholes, then drilling accuracy increases, but the complexity of controlling the trajectory and avoiding errors increases
Solution Approach 1:
The patent implements feedback by continuously measuring the distance to the pre-existing wellbore during drilling operations and using this information to adjust the drilling trajectory in real-time. The rotating magnet system provides continuous distance measurements that feed back to the drilling control system, enabling dynamic correction of trajectory deviations. This feedback mechanism simplifies trajectory control by providing real-time guidance rather than requiring complex pre-planned paths.
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 approach provides accurate distance measurement and trajectory control, minimizing errors and enhancing safety and efficiency in drilling operations by isolating the Earth's magnetic field interference and utilizing harmonics to correct signals, enabling precise parallel or intersecting borehole relationships.
Implementation Method 1
A time varying magnetic field is produced in the first borehole using a magnet in the second borehole. Magnetization in a magnetic object in the first borehole is produced.
Implementation Method 2
A coil in the second borehole is used to produce a signal responsive to a magnetic flux resulting from the magnetization.
Implementation Method 3
Estimating the distance may further include filtering of the signal to remove an effect of a magnetic field of the earth.
Data Source
AI summary
A rotating, transversely magnetized, magnet on a drill collar induces magnetization in a casing of a preexisting well. A coil rotating synchronously with the magnet produces a current at twice the frequency of rotation and having an amplitude that depends upon the distance from the magnet to the preexisting well. Alternatively, a variable magnetic field is produced in the casing using a switchable magnet.