Reconstructed Wavefield Imaging for Seismic Migration Artifacts
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Solution Overview
Problem
Conventional seismic imaging techniques face challenges in achieving high-resolution images with accurate migration amplitude and suffer from migration artifacts, especially in subsurface regions with sharp velocity contrasts.
Innovation Solution
The implementation of reconstructed wavefield imaging (RWI) in the time domain, which involves forward and backward propagation of seismic waves to improve image focusing and reduce migration artifacts by adapting the wavefield method, allowing for better subsurface structure visualization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional seismic imaging techniques are used, then the imaging process is simple and fast, but the image resolution and migration amplitude accuracy are insufficient
Solution Approach 1:
The imaging process is divided into multiple stages: wavefield separation into downgoing and upgoing waves, reconstruction of the downgoing wavefield, and subsequent migration imaging. This segmentation allows each stage to be optimized independently, improving overall image resolution while managing computational complexity through systematic breakdown of the imaging workflow
Solution Approach 2:
The downgoing wavefield is reconstructed before the migration imaging step. By performing this preliminary reconstruction using the recorded upgoing wavefield and estimated downgoing wavefield, the subsequent migration process benefits from pre-processed, high-fidelity wavefield data, thereby improving image resolution and migration amplitude accuracy
2Reliability
If conventional migration techniques are used, then the processing is computationally efficient, but migration artifacts appear especially in regions with sharp velocity contrasts
Solution Approach 1:
The method utilizes the recorded upgoing wavefield, which traditionally contains only reflection information, and combines it with an estimated downgoing wavefield to reconstruct the full two-way wavefield. This converts the limitation of having only one-way wavefield data into a benefit by enabling accurate reconstruction of the downgoing wavefield through the relationship between incident and reflected waves, thereby improving image accuracy in regions with sharp velocity contrasts
Solution Approach 2:
The reconstruction process uses feedback from the recorded upgoing wavefield to iteratively improve the estimated downgoing wavefield. By incorporating the actual recorded data into the reconstruction algorithm, the method continuously refines the wavefield estimates, reducing migration artifacts and improving reliability of the final image
3Measurement precision
If high-resolution imaging is pursued, then image quality improves, but computational cost and processing time increase significantly
Solution Approach 1:
The method reconstructs only the downgoing wavefield component that is needed for migration imaging, rather than processing the entire wavefield data. By focusing computational resources on reconstructing specifically the downgoing wavefield using the relationship between incident and reflected waves, the method achieves high image quality while reducing unnecessary computational overhead and processing time
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
RWI provides high-resolution seismic images with improved focusing and true migration amplitude, effectively reducing migration artifacts and enhancing the imaging of subsurface regions with sharp velocity contrasts.
Implementation Method 1
forward propagating a source signal to generate a forward-propagated wavefield
Implementation Method 2
back propagating the recorded data to generate a back-propagated wavefield
Implementation Method 3
cross correlating the forward-propagated wavefield and the back-propagated wavefield to generate images
Data Source
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AI summary
Computer systems and methods are provided for time domain reconstructed seismic wavefield imaging. The original source signal or extended source can be forward propagated based on a model of a subsurface region, in order to generate a residual by comparison to field data. The residual can be back-propagated to generate a reconstructed source signal, which can be forward propagated to generate a reconstructed source wavefield. Seismic images can be generated by cross correlating the forward-propagated reconstructed source wavefield and the back-propagated receiver wavefield. The model can include seismic parameters such as velocity, density, anisotropy and attenuation characterizing the subsurface region, and can be iteratively refined to improve image quality, based on the reconstructed source wavefield in comparison to the field data.