Multi-Sensor Airborne EM System Gradient Noise Cancellation
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Solution Overview
Problem
Existing EM surveying systems are not sensitive to near surface formation detection due to signals being buried in ambient or geologic noise.
Innovation Solution
A multi-sensor EM system that includes a transmitter for generating a primary EM field, a receiver for recording the secondary EM field, and a gradient sensor for measuring the gradient of the secondary EM field, all attached to a frame suitable for airborne surveys, allowing simultaneous recording of EM signals and their gradients to enhance detection of near surface formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional EM surveying system is used, then the system structure is simple, but the sensitivity to near surface formation detection is insufficient due to signals being buried in ambient or geologic noise
Solution Approach 1:
The system segments the measurement function by separating the measurement of the secondary EM field (performed by the receiver) from the measurement of its gradient (performed by the gradient sensor). This segmentation allows each sensor to optimize for its specific measurement type, improving overall sensitivity to near surface formations while managing system complexity through functional division.
Solution Approach 2:
The system merges multiple sensor types (receiver and gradient sensor) into a single integrated airborne EM surveying system. By combining these sensors and simultaneously recording both the secondary EM field and its gradient, the system achieves enhanced sensitivity to near surface formations that cannot be obtained with either sensor type alone.
2Measurement precision
If only a receiver is used to record the secondary EM field, then the device complexity is low, but the ability to detect near surface formations is limited due to ambient noise
Solution Approach 1:
The gradient sensor acts as an intermediary measurement device that captures the spatial gradient of the secondary EM field. This gradient information serves as a mediator that, when combined with the receiver data, enables the cancellation of ambient and geologic noise, thereby improving the detection capability for near surface formations.
Solution Approach 2:
The system replaces the conventional single-sensor mechanical approach with a multi-sensor measurement system that uses gradient sensing. This substitution allows for mathematical processing of gradient data to eliminate noise components, achieving superior detection capability without requiring increases in transmitter power or other mechanical modifications.
3Measurement precision
If the system records both secondary EM field and its gradient, then the sensitivity to near surface targets is improved, but the data processing complexity increases
Solution Approach 1:
The system uses feedback processing where the recorded gradient information is fed back into the data processing algorithm to cancel out ambient and geologic noise components. This feedback mechanism allows the system to iteratively improve the signal-to-noise ratio, enhancing sensitivity to near surface, lateral, and vertical conductive targets while managing processing complexity through systematic noise reduction.
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 system increases sensitivity to near surface, lateral, and vertical conductive targets by canceling primary fields and ambient noise, enabling more effective detection of subsurface features.
Implementation Method 1
EM surveys may be based on a controlled source that generates a primary EM field which carries EM energy into the earth, which induces eddy currents in the earth. The eddy currents generate a secondary EM field or ground response.
Implementation Method 2
a gradient sensor device attached to the frame and configured to record a gradient of the secondary EM field
Data Source
AI summary
A multi-sensor electromagnetic (EM) system and method for measuring gradients of EM signals. The multi-sensor EM system includes a frame; a transmitter device attached to the frame and configured to generate a primary EM field; a receiver device attached to the frame and configured to record a secondary EM field generated by the earth after being excited by the primary EM field; and a gradient sensor device attached to the frame and configured to record a gradient of the secondary EM field.