Seismic Adaptive Focusing via Time-Shift Extended Imaging
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Solution Overview
Problem
Seismic imaging in complex geological environments, such as those with salt structures, is hindered by inadequate velocity models, leading to poor image quality due to short-wavelength time shift distortions and unreliable data contributions, which are not effectively addressed by current methods.
Innovation Solution
An adaptive focusing technique that applies extended imaging conditions with positive and negative time shifts to correct image alignment errors, weight data based on reliability, and reduce contributions from unreliable parts, thereby improving image quality without requiring an updated velocity model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional seismic migration is used with inadequate velocity models, then processing speed is maintained, but image quality deteriorates due to short-wavelength time shift distortions
Solution Approach 1:
The patent segments the imaging process into multiple components: migration imaging with initial velocity model, adaptive focusing using cross-correlation of migrated traces, and weighted stacking. This segmentation allows each component to address specific aspects of image quality without requiring complete redesign of the entire processing pipeline.
Solution Approach 2:
The patent changes the imaging condition parameters by introducing time-shifted extended imaging conditions with variable time lags (τ) and shot indices (s). This allows the system to adapt to velocity model inaccuracies by adjusting these parameters dynamically during the imaging process, improving image quality without fundamentally changing the migration approach.
2Manufacturing precision
If velocity model accuracy is improved through more rigorous estimation technologies, then image quality improves, but computing time and computational resources increase significantly
Solution Approach 1:
The patent performs preliminary migration imaging using an initial velocity model to create migrated traces, which are then used in cross-correlation analysis to determine adaptive focusing parameters. This preliminary action enables subsequent image improvement without requiring complete reprocessing with highly accurate velocity models, thus reducing total computing time.
Solution Approach 2:
The patent creates a virtual copy of the migration process by applying time-shifted extended imaging conditions to the migrated traces. This copying allows the system to simulate different imaging scenarios and focus on specific regions of interest without re-executing the full migration process, thereby reducing computational resources required for image quality improvement.
3Manufacturing precision
If salt body delineation is performed with fine-tuning of salt geometry, then image accuracy improves, but labor and computational effort increase significantly
Solution Approach 1:
The patent enables the imaging system to self-correct by using cross-correlation of migrated traces to automatically determine time shifts and focusing parameters. This self-service mechanism allows the system to adapt to salt body complexities and velocity model inaccuracies without requiring manual fine-tuning or interpretation, thereby improving processing efficiency while maintaining accuracy.
Solution Approach 2:
The patent implements feedback by using the cross-correlation results from migrated traces to adjust the imaging conditions and weighting factors. This feedback loop allows the system to continuously refine the image quality based on the actual data characteristics, particularly in challenging salt body environments, without requiring manual intervention or reprocessing.
4Reliability
If extended imaging conditions with multiple time shifts are applied, then image reliability improves, but data processing complexity increases
Solution Approach 1:
The patent applies local quality by using shot-indexed gathers and weighting factors that are specific to each shot and region. The extended imaging conditions are applied locally to each shot-record combination, allowing the system to optimize image reliability for each local area without requiring complex global adjustments. This localized approach manages complexity while improving overall image reliability.
Data Source
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AI summary
A method for use in seismic exploration comprises: accessing a set of seismic data representative of a subterranean geological formation and a subsurface attribute model of the subterranean geological formation; performing a wavefield extrapolation on the seismic data in the subsurface attribute model; applying the time-shift extended imaging condition to the extrapolated wavefields; forming shot-indexed, time shift gathers for each image pixel of the subsurface attribute model from the conditioned extrapolated wavefields; adaptively focusing the gathers; and stacking the adaptively focused gathers; and imaging the subterranean geological formation from the stacked, adaptively focused gathers. The method may, in some aspects, be realized by a computing apparatus programmed to perform the method or as a set of instructions encoded on a non-transitory program storage medium that, when executed by a computing apparatus, perform the method.