De-aliased Source Separation in Marine Seismic Imaging
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Solution Overview
Problem
Current marine seismic surveying techniques face challenges in separating recorded signals from multiple simultaneously emitting sources, known as the 'simultaneous source problem, which hinders efficient 3D reflection seismic imaging of complex Earth subsurface structures.
Innovation Solution
The method employs modulation techniques, coordinate transformations, and cyclic convolution to separate wave fields generated by multiple sources in the frequency-wavenumber domain, utilizing concepts like seismic apparition and NMO correction to isolate and de-alias signals, allowing for the reconstruction of individual source data from blended recordings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple sources emit signals simultaneously to increase data acquisition efficiency, then productivity is improved, but the recorded signals become aliased and mixed making source separation difficult
Solution Approach 1:
The patent applies periodic modulation to at least one of the multiple sources, causing the sources to emit signals in a periodic pattern rather than continuously. This periodic action creates distinct temporal signatures for each source, enabling separation of their contributions to the blended signal while maintaining simultaneous operation for improved productivity
Solution Approach 2:
The patent modulates parameters such as frequency, amplitude, or phase of the signals emitted by multiple sources. By changing these parameters periodically or in distinctive patterns, each source's signal becomes identifiable within the blended recording, resolving the aliasing problem while maintaining simultaneous emission for efficient data acquisition
2Measurement precision
If sources are activated sequentially to avoid signal mixing, then measurement precision is improved, but loss of time increases due to slower data acquisition
Solution Approach 1:
The patent enables continuous simultaneous operation of multiple sources through modulation techniques. Instead of sequential activation, multiple sources operate continuously and simultaneously with modulated signals that can be separated afterward, eliminating idle time between source activations and dramatically reducing total data acquisition time while maintaining signal separation capability
3Measurement precision
If modulation techniques are applied to separate source signals, then signal separation accuracy is improved, but device complexity increases due to additional processing requirements
Solution Approach 1:
The patent replaces complex mechanical or physical separation systems with signal processing-based separation using modulation techniques. Instead of physically separating source signals through complex hardware, the invention uses mathematical transformations and spectral analysis to separate modulated signals, reducing mechanical complexity while improving separation accuracy
Data Source
AI summary
Methods are described for separating the unknown contributions of two or more sources from a commonly acquired aliased wave field signals including the determination of models with reduced support in the frequency-wavenumber domain which reconstruct the wave fields of independently-activated sources after a coordinate-transform of the acquired wave field data and/or in a coordinate-transformed domain.