Pre-stack High-angle FFT Seismic Imaging for Complex Structures
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Solution Overview
Problem
Traditional seismic imaging methods, such as those based on the first-order Born-approximation split-step Fourier transform, are inadequate for high-angle structures like complex fault-block, strike-slip fault, and fractured buried-hill reservoirs due to low imaging quality, poor efficiency, and high dependence on accurate velocity models.
Innovation Solution
A seismic imaging method and system utilizing pre-stack high-angle fast Fourier transform (FFT) that involves data acquisition, conversion to frequency-wavenumber domain, calculation of wave propagation angles, optimization of constant coefficients using an improved random walk algorithm, and frequency-division layer-by-layer wavefield continuation to achieve high-precision imaging of high-angle structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional split-step Fourier transform is used for seismic imaging, then computational efficiency is maintained, but imaging quality deteriorates for high-angle structures
Solution Approach 1:
The imaging region is divided into multiple sub-regions based on wave propagation angles. Different imaging operators are applied to different sub-regions: high-angle operators for steep structures and low-angle operators for gentle structures. This segmentation allows each region to be processed with the most appropriate operator, improving overall imaging quality while maintaining computational efficiency through targeted processing.
Solution Approach 2:
The patent introduces angle-dependent parameters into the imaging operator, including wave propagation angle thresholds and region-specific coefficients. By changing parameters based on local geological conditions and wave angles, the method adapts to both high-angle and low-angle structures, resolving the contradiction between maintaining computational efficiency and improving imaging quality across diverse structures.
2Manufacturing precision
If high-accuracy imaging techniques such as least-squares reverse-time migration are used, then imaging quality of high-angle structures is improved, but computational efficiency deteriorates to extremely low levels
Solution Approach 1:
The patent replaces the computationally intensive least-squares reverse-time migration mechanism with an optimized Fourier-based imaging approach. By substituting the time-domain iterative solving mechanism with frequency-domain analytical solutions and closed-form operators, the method achieves high imaging quality for steep structures while maintaining computational efficiency at industrial application levels.
Solution Approach 2:
The method changes the fundamental parameters of the imaging approach by transitioning from time-domain iterative methods to frequency-domain analytical methods. This parameter change in the mathematical domain enables high-accuracy imaging of high-angle structures without the extreme computational cost associated with traditional least-squares reverse-time migration.
3Reliability
If traditional seismic imaging methods are used, then computational speed is maintained, but imaging quality deteriorates due to high dependence on accurate velocity models
Solution Approach 1:
The patent introduces dynamic adaptation into the imaging process by making the imaging operator adaptive to local wave propagation conditions. The method dynamically adjusts imaging parameters and selects appropriate operators based on calculated wave angles and local velocity characteristics, reducing dependence on globally accurate velocity models while improving imaging quality in complex high-angle structures.
Solution Approach 2:
The method changes velocity model dependency by introducing angle-based parameters and region-specific coefficients that compensate for velocity model inaccuracies. By parameterizing the imaging operator with locally adapted values rather than relying solely on global velocity model accuracy, the method reduces sensitivity to velocity model errors while maintaining high imaging quality.
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 method achieves highly precise seismic imaging of high-steep structures with angles up to 60°, improving imaging efficiency and making it suitable for industrial applications, while reducing reliance on accurate velocity models.
Implementation Method 1
converting time-space domain common offset seismic data in the time-space domain common offset gather from time-space domain to frequency-wavenumber domain by using Fourier transform to obtain frequency-wavenumber domain common offset seismic data
Data Source
AI summary
This disclosure relates to geophysical exploration and seismic imaging, and more particularly to a seismic imaging method, system, and device based on pre-stack high-angle fast Fourier transform (FFT). The method includes: acquiring seismic data acquired during seismic exploration; extracting a common shot point gather from the seismic data followed by conversion into a frequency wavenumber domain common offset gather; calculating wave propagation angles; dividing an imaging region into a first region and a second region; solving constant coefficients of the first region and the second region; performing frequency-division layer-by-layer wavefield continuation on a frequency-wave number domain common offset gather to obtain imaging results at different depths and frequencies; subjecting the imaging results to integration followed by transformation to a spatial domain to obtain common offset imaging profiles; and subjecting the common offset imaging profiles to superposition obtain final imaging results. The disclosure achieves the highly-precise seismic imaging of high-steep structures and improves imaging efficiency.