Seismic Imaging Using Diffraction and Refraction Wavefield Decomposition
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Solution Overview
Problem
Current seismic imaging techniques face challenges in accurately identifying geologic features, particularly in the near-surface region, due to complexities such as shingle waves and tail waves, which complicate velocity measurement and imaging.
Innovation Solution
A low-frequency reverse time migration (RTM) imaging condition-based technique that uses diffracted and refracted seismic waves, decomposing wavefields into vertical and horizontal components, applying Hilbert transforms to noise terms, and generating wave-path tracking data to enhance seismic image resolution and reduce computation costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional seismic imaging techniques are used, then imaging coverage is achieved, but spatial resolution is insufficient and computation costs are high
Solution Approach 1:
The patent segments the seismic wavefield into up-going and down-going components through wavefield decomposition. This segmentation allows selective processing of different wave types (diffracted vs. reflected waves) and enables the imaging system to focus computational resources on generating high-resolution images of specific geologic features while reducing overall computation costs by at least 50%
Solution Approach 2:
The patent applies Hilbert transforms to convert the segmented wavefields into analytic signals, effectively adding an imaginary dimension to the real wavefield data. This dimensionality change enables the extraction of envelope information that represents spatial resolution enhancement, allowing the system to achieve higher spatial resolution in the final seismic image
2Reliability
If conventional RTM imaging is used, then seismic images are generated, but low-frequency noise terms reduce image quality
Solution Approach 1:
The patent converts the harmful low-frequency noise terms into useful information by applying Hilbert transforms to extract envelope signals. Instead of filtering out these noise terms as conventional methods do, the invention transforms them into analytic signals that contain valuable spatial resolution information about diffracted and refracted seismic waves, thereby improving image quality while eliminating the harmful effects of low-frequency noise
3Measurement precision
If wavefield decomposition is applied, then imaging precision is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal wavefield decomposition framework that handles multiple wave types (diffracted, refracted, and reflected waves) and multiple imaging objectives through a single integrated processing system. The decomposition module serves multiple functions: separating up-going and down-going waves, enabling analytic signal generation, and facilitating selective imaging of different geologic features, thereby improving imaging precision without proportionally increasing processing complexity
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 provides high-resolution structural and stratigraphic sections, effectively distinguishing geologic features like fault surfaces and fracture zones, while reducing computation costs by at least 50% compared to conventional methods.
Implementation Method 1
The seismic wave travels into the ground, is reflected by subsurface formations, and returns to the surface where it is recorded by sensors called geophones
Implementation Method 2
Rather than applying a Hilbert transform to the RTM image, the seismic imaging system applies the Hilbert transform to the low frequency RTM noise
Implementation Method 3
Source and receiver wavefields are decomposed into their respective vertical and horizontal directions
Implementation Method 4
a low-frequency reverse time migration (RTM) imaging condition-based technique to image subsurface geologic features using diffracted and refracted seismic waves
Implementation Method 5
a low-frequency reverse time migration (RTM) imaging condition-based technique to image subsurface geologic features using diffracted and refracted seismic waves
Data Source
AI summary
A process for seismic imaging of a subterranean geological formation includes generating a source wavefield from seismic data representing a subterranean formation. The process includes generating a receiver wavefield from the seismic data representing the subterranean formation. The process includes decomposing the source wavefield to extract a source depth component and decomposing the receiver wavefield to extract a receiver depth component. The process includes applying a transform to each of the source depth component and the receiver depth component. The process includes combining the source depth component and the receiver depth component to generate an imaging condition. The process includes extracting a low-frequency term from the imaging condition to generate a wave-path tracking data, generating a wave path from the wave-path tracking data, and rendering a seismic image of at least a portion of the subterranean geological formation from the generated wave path.