Seismic Wavefield Filter for Artifact Reduction
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Solution Overview
Problem
Current seismic data processing techniques, such as reverse time migration, often produce strong low-wavenumber artifacts in shallow parts and near interfaces due to interference from wide-angle diving waves and back-scattering energy, which are difficult to filter effectively across a wide range of angles without increasing computational complexity.
Innovation Solution
A method involving the application of a wavefield filter that attenuates wavefields in specific directions, using a time derivative formula that combines the original time derivative of wavefields with a product of a wave function and spatial gradient, allowing for directional filtering across all computational domains with adjustable angles and reduced computational expense.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reverse time migration is used to image subsurface formations, then imaging quality for complex structures is improved, but strong low-wavenumber artifacts are generated in shallow parts and near interfaces
Solution Approach 1:
The patent extracts and removes harmful wavefield components (diving waves and back-scattered energy) from the total wavefield using directional filtering based on the Poynting vector. By separating the useful reflected energy from the harmful interfering energy, the method eliminates low-wavenumber artifacts while preserving imaging quality for complex structures.
Solution Approach 2:
The patent converts the harmful interference patterns into useful information by using the Poynting vector to identify and characterize the direction of energy propagation. The interfering diving waves and back-scattered energy, which normally degrade image quality, are systematically identified and removed, transforming the problem of interference into a solution for artifact elimination.
2Object-generated harmful factors
If post-imaging filtering is applied to suppress artifacts, then artifact reduction is achieved, but computational complexity increases
Solution Approach 1:
The patent applies filtering during the wavefield propagation process itself, before the final imaging step. By incorporating directional filtering into the migration algorithm and using the Poynting vector to guide the filtering operation, the method removes artifacts during data processing rather than requiring separate post-processing steps, thereby reducing overall computational complexity.
3Object-generated harmful factors
If directional filtering is applied to remove interference wavefields, then artifact reduction is improved, but computational expense increases
Solution Approach 1:
The patent uses the Poynting vector, which is naturally computed during the reverse time migration process, to provide directional information for filtering. This self-service approach leverages existing computational outputs (the Poynting vector from the wavefield propagation) to guide the filtering operation, avoiding the need for additional expensive directional analysis or multiple filtering passes.
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 effectively attenuates undesirable wavefields propagating in target directions, enhancing the quality of seismic images by reducing artifacts and improving the accuracy of wave propagating direction evaluation, while maintaining computational efficiency.
Implementation Method 1
applying a wavefield filter to the plurality of full wavefields to obtain a plurality of filtered wavefields
Implementation Method 2
Fletcher et al. (2005) proposed to remove the noise by applying a directional damping term to modified non-reflection wave equation
Data Source
AI summary
A method for seismic processing includes steps of receiving seismic data comprising seismic waveforms acquired from a plurality of seismic receivers and a plurality of seismic sources in a subterranean area; generating a plurality of full wavefields at a plurality of corresponding propagation time steps based on a seismic velocity and a density model of the subterranean area; and applying a wavefield filter to the plurality of full wavefields to obtain a plurality of filtered wavefields. Each of the plurality of full wavefields propagates in all directions. On the other hand, each of the plurality of filtered wavefields is attenuated in or opposite to a target direction. The target direction is selected by the user.