Hybrid One-way Full-way Wave Equation Migration for Seismic Imaging
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Solution Overview
Problem
One-way wave equation migration methods fail to accurately image complex geologic structures due to neglecting turning waves and duplex waves, while full-way wave equation migration is computationally expensive and generates strong wavefield noise, especially in 3D seismic imaging.
Innovation Solution
The Hybrid One-way and Full-way (HOF) wave equation migration method, which extrapolates seismic wavefields using a one-way wave equation in less complex media and a full-way wave equation in complex media, applying frequency-space and time-space domain imaging conditions respectively, and introduces an amplitude matching factor to form the final subsurface image, thereby reducing noise and computational resources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If full-way wave equation migration is used, then image quality for complex geologic structures is improved, but computational cost and wavefield noise increase significantly
Solution Approach 1:
The patent divides the migration process into two segments: one-way wave equation migration for the entire model and full-way wave equation migration only for the target area with complex structures. This segmentation allows the method to achieve high image quality in complex regions while maintaining computational efficiency in simpler regions, resolving the contradiction between image quality and computational cost.
Solution Approach 2:
The patent applies different migration methods to different regions: one-way migration for areas with smoothly varying velocity and full-way migration for the target area with complex geologic structures. This local differentiation ensures high image quality where needed while minimizing computational overhead in other areas, effectively balancing image quality and computational efficiency.
2Measurement precision
If full-way wave equation migration is used, then image quality for complex geologic structures is improved, but wavefield noise increases
Solution Approach 1:
The patent segments the migration domain into a target area with complex structures and surrounding areas with simpler structures. By applying full-way migration only to the target area and one-way migration elsewhere, the method reduces the overall wavefield noise while maintaining image quality in the critical complex regions.
Solution Approach 2:
The patent uses an amplitude matching factor as an intermediary to combine the results from one-way and full-way migrations. This intermediary element allows the method to leverage the low-noise advantage of one-way migration in most areas while incorporating the high-quality imaging capability of full-way migration only where necessary, thus reducing overall wavefield noise.
3Productivity
If one-way wave equation migration is used, then computational efficiency is improved, but image quality for complex structures deteriorates
Solution Approach 1:
The patent segments the migration process to apply one-way wave equation migration for the bulk of the model and full-way wave equation migration only for the target area with complex structures. This segmentation preserves computational efficiency for the majority of the computation while enhancing image quality specifically in regions where complex geologic structures require the more accurate full-way method.
Solution Approach 2:
The patent applies local quality by using one-way migration in regions with smoothly varying velocity and full-way migration in the target area with complex geologic structures. This ensures that computational efficiency is maintained in simpler regions while image quality is improved in complex regions, resolving the contradiction between these two parameters.
4Adaptability or versatility
If full-way wave equation migration is used, then coverage of turning waves and duplex waves is improved, but memory and disk space requirements increase
Solution Approach 1:
The patent segments the computational domain into a target area requiring full-way migration for complete wave mode coverage and surrounding areas where one-way migration suffices. This segmentation reduces the overall memory and disk space requirements while maintaining comprehensive wave mode coverage in the critical target area where complex structures demand it.
Data Source
AI summary
A migration method using hybrid one-way and full-way (HOF) wave equation propagation. The HOF method extrapolates seismic wavefields in less complex media with a one-way wave equation propagator and extrapolates seismic wavefields in extremely complex media with a full-way wave equation propagator. For prestack depth migration, the HOF extrapolates source-side and receiver-side wavefields independently. Frequency-space domain and time-space domain imaging conditions are applied to the one-way and the full-way extrapolated wavefields, respectively. A suitable amplitude matching factor is introduced to combine the one-way and full-way images. The HOF method is a cost-effective migration that produces superior image quality with less noises and less computational resources.