Post-Imaging Deghosting Marine Seismic Data
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Solution Overview
Problem
Marine seismic data is contaminated by source and receiver 'ghost' effects, which limit temporal resolution, introduce spectral notches, and complicate data processing, especially in pre-migration stages, due to spurious reflections from the free sea surface.
Innovation Solution
The method involves post-imaging deghosting using discrete multi-dimensional impulse response filters to approximate the Hessian operator, allowing for the deconvolution of ghost effects from the data, enabling more accurate imaging and reflectivity estimation while maintaining 3-D wavefield characterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional pre-stack deghosting is applied early in processing, then subsequent velocity analysis benefits from sharper wavelet, but spatial sampling limitations and spectral distortions are not fully overcome
Solution Approach 1:
The patent applies preliminary deghosting processing early in the workflow to improve wavelet sharpness for velocity analysis, while preserving the option to apply additional deghosting later. This staged approach allows early benefits without committing to complete deghosting before migration, thereby preserving spatial sampling information for later recovery.
Solution Approach 2:
The deghosting process is segmented into multiple stages: initial deghosting before migration for velocity analysis, followed by post-migration deghosting to recover spatial sampling information and remove remaining spectral distortions. This segmentation allows each stage to optimize for its specific purpose without compromising overall information quality.
2Manufacturing precision
If complete deghosting is applied before migration, then wavelet sharpness is improved, but ghost effects may be incompletely removed due to spatial sampling limitations
Solution Approach 1:
The patent applies preliminary deghosting to improve wavelet sharpness for migration and velocity analysis, while recognizing that complete ghost removal is achieved only after migration. This preliminary action prepares the data for processing without claiming complete ghost elimination at that stage.
Solution Approach 2:
Migration acts as an intermediary step that transforms the data in a way that enables more effective deghosting. By migrating first, the data geometry changes to allow subsequent deghosting operators to more completely remove ghost effects, overcoming the limitations of pre-migration deghosting.
3Reliability
If post-imaging deghosting is applied, then signal-to-noise ratio is enhanced and spatial sampling characterization is improved, but processing complexity increases
Solution Approach 1:
The patent applies necessary deghosting processing before migration to enable proper velocity analysis and imaging. The more complex post-imaging deghosting is then applied to enhance signal-to-noise ratio and recover spatial sampling information, accepting the increased complexity because it produces superior final results.
Solution Approach 2:
The patent changes the processing parameters and approach based on the imaging stage. Pre-migration deghosting uses parameters optimized for wavelet sharpness, while post-imaging deghosting uses parameters optimized for signal-to-noise ratio and spatial sampling recovery. This parameter adaptation manages complexity by using appropriate methods for each stage.
4Productivity
If early pre-stack deghosting is used, then processing efficiency is maintained, but spectral notches and distortions persist
Solution Approach 1:
The deghosting process is segmented into early efficient processing that maintains productivity, and later processing that recovers spectral information. The early stage removes obvious ghost effects to maintain processing efficiency, while the post-imaging stage recovers spectral notches and distortions that would be too computationally intensive to remove earlier.
Solution Approach 2:
The patent maintains continuous deghosting action throughout the processing workflow rather than performing a single comprehensive deghosting operation. This continuous approach removes ghost effects at multiple stages, progressively improving spectral quality while maintaining overall processing efficiency through staged rather than monolithic processing.
Data Source
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AI summary
A technique includes determining an image of a subsurface geologic region of interest, where the image represents at least in part ghost energy that is attributable to reflections caused by a reflecting interface. The technique includes deghosting the image, which includes processing data representing the image in a processor-based machine to determine at least one impulse response of a modeling and migration of at least one point scatterer for the region and use the impulse response(s) to attenuate the ghost energy.