Seismic Diffraction Imaging via Two-Wavefield Decomposition
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Solution Overview
Problem
Current seismic imaging techniques, particularly one-way imaging conditions, face challenges in efficiently imaging subsurface geologic features like faults and fractures due to high computational costs and limited illumination, often missing valuable information from up-going wavefields.
Innovation Solution
The implementation of a two-way imaging condition-based technique that decomposes source and receiver wavefields into specific propagating components, allowing for the generation of positive-dip and negative-dip structure images without up-down wavefield separation, which enhances diffraction imaging by incorporating both down-going and up-going wavefields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If one-way imaging condition is used, then computation cost is reduced, but illumination coverage is limited and up-going wavefield information is lost
Solution Approach 1:
The patent segments the two-way wavefield into down-going and up-going components using directional filtering in the spatial-frequency domain. This allows selective use of wavefield components for imaging, achieving efficient computation while preserving illumination coverage. The segmentation is performed by applying directional filters to separate wave propagation directions before imaging.
Solution Approach 2:
The patent transforms the wavefield representation by changing the parameter domain from time-space to spatial-frequency domain. This parameter change enables efficient separation of wave propagation directions through filtering operations, allowing the system to achieve both computational efficiency and complete illumination coverage by selectively combining down-going and up-going wavefield contributions.
2Measurement precision
If up-down wavefield separation is performed, then diffraction imaging accuracy is improved, but computation cost increases significantly
Solution Approach 1:
The patent replaces the traditional mechanical/time-domain wavefield separation methods with a frequency-domain filtering approach. By transforming to the spatial-frequency domain and applying directional filters, the system achieves accurate diffraction imaging without the high computational cost of traditional up-down separation methods. This substitution of the separation mechanism reduces complexity while maintaining precision.
3Productivity
If traditional seismic imaging is used, then computational efficiency is maintained, but spatial resolution of faults and fractures is insufficient
Solution Approach 1:
The patent maintains continuous useful action by incorporating both down-going and up-going wavefield contributions in the imaging process. This continuous utilization of all available wavefield information enhances the spatial resolution of faults and fractures while maintaining computational efficiency through the frequency-domain implementation. The continuous action ensures no useful diffraction information is lost.
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 reduces computation costs by approximately 40% and provides broader illumination, enabling the detection of faults and fractures with higher spatial resolution and improved subsurface feature imaging.
Implementation Method 1
The seismic source is typically located at ground surface. The seismic wave travels into the ground, is reflected by subsurface formations, and returns to the surface
Implementation Method 2
This disclosure describes systems and methods for an efficient two-way imaging condition-based technique to image subsurface geologic features using diffracted seismic waves
Implementation Method 3
Source and receiver wavefields are decomposed into their respective right-down/left-up and left-down/right-up propagating waves
Implementation Method 4
An imaging condition for generating both a positive-dip structure image and a negative-dip structure image is the inner product of the wavefields
Implementation Method 5
Applying the sample-by-sample multiplication imaging condition to the opposite dip images, the diffraction energy is retained while the reflection energy is significantly attenuated
Data Source
AI summary
A system for seismic imaging of a subterranean geological formation uses a two-way imaging condition. A seismic signal is emitted into a subterranean formation and recorded at receiver(s). Source and receiver wavefields are decomposed into respective right-down/left-up and left-down/right-up propagating waves. The right-down/left-up and left-down/right-up direction can be defined along the direction emitted from the source or receiver to corresponding direction in two dimensional (2D) case. An imaging condition for generating both a positive-dip structure image and a negative-dip structure image is the inner product of the wavefields. Applying the sample-by-sample multiplication imaging condition to the opposite dip images, the diffraction energy is retained while the reflection energy is significantly attenuated. The diffraction image can be used to detect faults and fractures in subsurface regions.