Seismic Imaging Fourier Domain Phase Rotation
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Solution Overview
Problem
Conventional seismic imaging methods, such as full waveform inversion (FWI), struggle to accurately image subsurface geology with conflicting dips, particularly at faults and salt flanks, leading to attenuation of reflectors with different dips, which hinders the identification of hydrocarbon deposits and poses challenges in drilling and production operations.
Innovation Solution
A method involving transforming the FWI image into the Fourier domain, applying a multi-dimensional low-cut filter, phase rotating by 90 degrees, and performing an inverse Fourier transform to generate a new image that preserves conflicting dips, thereby improving seismic imaging in complex geological areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional FWI processing with directional derivative is applied, then processing speed is maintained, but imaging accuracy deteriorates in areas with conflicting dips
Solution Approach 1:
The patent transforms the conventional single-dip constraint into a multi-dip capability by introducing a dip field that can accommodate multiple dip values at each spatial location. This is achieved by modifying the directional derivative operator to accept a dip field with multiple dip components, allowing simultaneous representation of conflicting dip directions in fault and salt flank areas.
Solution Approach 2:
The patent changes the dip parameter from a single-value constraint to a multi-value field representation. By allowing the dip field to contain multiple dip angles and directions at each spatial location, the system can accurately represent complex geological structures with conflicting dips, thereby improving imaging accuracy in previously problematic areas.
2Measurement precision
If conventional single-dip field is used, then computational complexity is reduced, but imaging quality deteriorates at faults and salt flanks
Solution Approach 1:
The patent segments the dip field into multiple independent dip components that can be processed separately and then combined. This segmentation allows the complex multi-dip field to be managed through modular operations, reducing the overall computational complexity while maintaining the ability to represent conflicting dips accurately in fault and salt flank regions.
Solution Approach 2:
The patent creates a universal dip field framework that can handle both simple single-dip scenarios and complex multi-dip scenarios within the same computational structure. This multi-functional dip field implementation allows the system to adapt to varying geological complexity without requiring separate processing pipelines, thereby managing computational complexity effectively.
3Measurement precision
If directional derivative with fixed dip is applied, then processing simplicity is maintained, but reflector preservation deteriorates for different dips
Solution Approach 1:
The patent introduces dynamic dip field adjustment where the dip values are not fixed but can adapt to the local geological structure. The dip field is updated iteratively based on the imaging results, allowing the system to dynamically adjust to conflicting dips in fault and salt flank areas, thereby improving reflector preservation while managing algorithm complexity through iterative refinement.
Data Source
AI summary
A method is described for seismic imaging including receiving a full waveform inversion (FWI) image of a subsurface volume of interest including complex geology; transforming the FWI image to the Fourier domain to generate a Fourier domain image; performing a multi-dimensional low-cut filter of the Fourier domain image to generate a low-cut filter image; phase rotating by 90 degrees the low-cut filter image to generate a phase-rotated image; performing an inverse Fourier transform on the phase-rotated image to generate a transformed image; and displaying the transformed image on a graphical display. The method is executed by a computer system.