Electromagnetic Survey Data Processing via Seismic-Like Velocity Analysis
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Solution Overview
Problem
Conventional methods for acquiring and processing Continuous Source Electro-Magnetic (CSEM) survey data differ significantly from seismic data, and existing EM data processing techniques are sensitive to source strength and orientation, with strong attenuation and dispersion complicating the detection of hydrocarbons in subsurface formations.
Innovation Solution
Applying seismic-like acquisition and processing techniques to electromagnetic (EM) data, including the use of impulsive-source EM methods and seismic-style workflows such as semblance analysis, f-k transforms, and Radon transformations, to produce representations of subsurface formations and detect hydrocarbons based on moveout velocities rather than amplitudes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional CSEM data processing techniques are used, then the processing can be performed with existing methods, but the results are sensitive to source strength and orientation and suffer from strong attenuation and dispersion
Solution Approach 1:
The patent replaces conventional CSEM processing methods with seismic-like processing techniques. Specifically, it applies seismic acquisition and processing workflows including semblance analysis, f-k transforms, and Radon transformations to electromagnetic data, substituting the mechanical/mathematical processing system to achieve more robust hydrocarbon detection that is less sensitive to source characteristics and attenuation effects
Solution Approach 2:
The patent changes the fundamental processing parameters and approaches by treating electromagnetic data with seismic processing methodologies. This involves changing from amplitude-based analysis to moveout velocity-based analysis, and applying seismic-style velocity analysis and stacking operations to EM data, thereby transforming the processing paradigm to overcome attenuation and dispersion issues
2Measurement precision
If seismic-like acquisition and processing techniques are applied to EM data, then sensitivity to source strength and orientation is reduced and hydrocarbon detection is improved, but the processing methodology becomes more complex
Solution Approach 1:
The patent applies universal seismic processing techniques to electromagnetic data, making the seismic processing methodology multi-functional. By using the same seismic acquisition and processing workflows (semblance analysis, f-k transforms, Radon transformations) for both seismic and EM data, the system achieves improved hydrocarbon detection precision while the complexity is justified by the enhanced measurement precision and reduced sensitivity to source characteristics
3Reliability
If moveout velocity analysis is used instead of amplitude analysis, then hydrocarbon detection becomes more robust against attenuation and dispersion, but the processing requirements increase
Solution Approach 1:
The patent performs preliminary velocity analysis and moveout corrections before final hydrocarbon detection. By applying seismic-style velocity analysis and stacking operations early in the processing workflow, the method prepares the data in a way that makes subsequent hydrocarbon detection more robust against attenuation and dispersion effects, even though this preliminary processing increases overall processing requirements
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 reduces sensitivity to source strength and orientation, effectively detects hydrocarbons by analyzing moveout velocities, and provides more robust and accurate representations of subsurface electrical resistivity, overcoming the challenges of strong attenuation and dispersion in EM data.
Implementation Method 1
generating an electromagnetic pulse using an electromagnetic source at selected locations to induce electromagnetic energy propagation in the subsurface formations
Implementation Method 2
The electromagnetic energy returned from the subsurface formations is detected using a plurality of electromagnetic receivers
Data Source
AI summary
Systems and methods for acquiring and processing electromagnetic data in subsurface formations. In one example, a system includes an electromagnetic source, a plurality of electromagnetic receivers, and an electromagnetic data processor. The electromagnetic source is configured to generate an electromagnetic pulse that induces electromagnetic energy in subsurface formations. The electromagnetic receivers are configured to detect the electromagnetic energy reflected by the subsurface formations, and to output signals corresponding to detected electromagnetic energy reflected by the subsurface formations. The electromagnetic data processor configured to process, based on differences in travel times of the electromagnetic energy between the subsurface formations and the electromagnetic receivers, the signals output by the electromagnetic receivers. The electromagnetic data processor is further configured to produce a representation of the subsurface formations based on processed signals output by the electromagnetic receivers.