Marine Seismic Source Separation via Phase Encoding
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Solution Overview
Problem
Conventional marine seismic surveys face inefficiencies due to zero time overlap between shot records, leading to poorly sampled seismic data and interference from multiple sources, which complicates data processing and reduces the accuracy of subsurface imaging.
Innovation Solution
The method involves simultaneous shooting acquisition with multiple seismic sources, using a cost function to separate sources by minimizing the residual misfit between input and modeled data, employing phase encoding, and iterative inversion techniques with NMO corrections and multi-dimensional median filters to align and extract coherent signals, thereby reducing interference and enhancing data quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple seismic sources are activated simultaneously, then productivity is improved by reducing survey times, but measurement precision deteriorates due to interference from multiple sources and poorly sampled seismic data
Solution Approach 1:
The patent segments the blended seismic data by applying phase encoding to separate the contributions from multiple simultaneously activated sources. Each source's signal is encoded with a distinct phase signature, allowing computational separation of the mixed recordings into individual source components, thereby maintaining measurement precision while enabling simultaneous shooting
Solution Approach 2:
The patent transforms the seismic data from the time domain to the frequency domain through Fourier transformation, and applies NMO (normal moveout) corrections to align reflection events. These parameter transformations in the frequency-wavenumber domain enable coherent signal enhancement and interference suppression, resolving the precision issue while maintaining productivity benefits
2Productivity
If multiple seismic sources are activated simultaneously, then productivity is improved by continuous data recording, but device complexity increases due to the need for sophisticated separation algorithms and processing systems
Solution Approach 1:
The patent replaces complex mechanical timing coordination (activating sources at precisely staggered times) with computational phase encoding methods. Instead of mechanically controlling shot timing to avoid overlap, the system uses mathematical transformations in the frequency domain to separate simultaneously recorded signals, simplifying the acquisition hardware while maintaining processing capability through software-based separation algorithms
3Measurement precision
If conventional sequential shooting is used, then measurement precision is maintained with properly sampled data, but productivity deteriorates due to zero time overlap between shot records and extended survey times
Solution Approach 1:
The patent merges multiple seismic source activations into a single continuous recording by allowing temporal overlap of shot records. Instead of enforcing sequential timing with zero overlap, the system combines signals from multiple sources in the blended dataset and uses phase encoding to computationally separate them, achieving both continuous recording for productivity and precise separation for measurement quality
Data Source
AI summary
Seismic data are obtained by recording simultaneously in seismic streamer, acquired by activating approximately simultaneously two or more seismic sources towed at two positions in the vicinity of seismic streamers. A residual is updated iteratively for an inversion solution for the activations of the two or more seismic sources. The iterative updating of the residuals utilizes a sequence of overlapping temporal windows containing reflection events and utilizes normal moveout corrections based on largest reflection events in each temporal window. A final updated residual is added to a final updated model result.