CSEM Void Detection Using Bi-Static Doublet Responses
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Solution Overview
Problem
Existing techniques such as Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) are inadequate for detecting near-subsurface voids or karsts, posing safety risks and having various other detection needs.
Innovation Solution
Utilizing Controlled Source Electromagnetic (CSEM) methods with bi-static doublets and cross-correlation electromagnetic tomography, employing a PRN code and synchronized CSEM receivers to detect near-subsurface voids by analyzing electromagnetic responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Electrical Resistivity Tomography (ERT) or Ground Penetrating Radar (GPR) is used for void detection, then the detection can be performed with existing techniques, but the detection precision and reliability are insufficient
Solution Approach 1:
The patent changes the detection parameter from conventional resistivity or radar wave reflection to electromagnetic induction response. By using controlled source electromagnetic methods that measure induced electromagnetic fields rather than direct resistivity or radar reflections, the system achieves superior sensitivity to void structures and conductive elements, resolving the contradiction between measurement precision and detection reliability
Solution Approach 2:
The patent replaces conventional mechanical/electrical measurement systems (ERT electrodes, GPR antennas) with an electromagnetic induction-based system. This substitution enables detection of voids and conductive elements through electromagnetic field interactions, achieving higher precision and reliability compared to traditional methods
2Reliability
If conventional EM methods with multiple transmitters and complex receiver arrays are used, then detection capability is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates unnecessary components from conventional EM systems. By using a single transmitter and simplified receiver array that measures induced electromagnetic fields rather than direct signals, the system achieves equivalent or superior detection capability with reduced complexity, removing redundant transmitters and complex signal processing requirements
Solution Approach 2:
The patent introduces an intermediary measurement approach by measuring induced electromagnetic fields rather than direct transmitter-receiver signals. This intermediary measurement method simplifies the system architecture while maintaining detection capability, as the induced fields provide indirect but sensitive information about subsurface voids and conductors
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
Effectively identifies near-subsurface voids and conductive elements with high precision, providing accurate localization and characterization of subsurface structures.
Implementation Method 1
a CSEM transmitter transmits a signal into the ground
Implementation Method 2
an array of a plurality of surface CSEM receivers is deployed to record a response created by the CSEM transmitter
Implementation Method 3
The signal data and the received signal data are cross-correlated
Data Source
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AI summary
A system and techniques for detecting near-subsurface voids in the earth use a controlled source electromagnetic transmitter and a plurality of controlled source electromagnetic receivers. Signals received by the plurality of controlled source electromagnetic receivers corresponding to signals generated by the controlled source electromagnetic transmitter are analyzed. Bi-static doublets detected in the received signals are used to identify the location of the near-subsurface voids.