Equal Area Spherical Binning for RTM Image Angle Gathers
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Solution Overview
Problem
Conventional seismic data processing methods, particularly in marine seismic exploration using ocean bottom nodes, face challenges with angular binning due to sensitivity to data sampling, leading to over-sampling near angles and under-sampling far angles, which affects the quality and amplitude behavior of image gathers.
Innovation Solution
The implementation of an equal area spherical binning technique for seismic data processing using reverse time migration (RTM) to define incident and azimuth angle bins at reflection points, providing a more uniform distribution and adaptability to different acquisition geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional cylindrical binning is used for RTM angle gathers, then the binning process is simple to implement, but the angular bins become non-uniform in area causing over-sampling near angles and under-sampling far angles
Solution Approach 1:
The patent transforms the binning approach from cylindrical coordinates to spherical coordinates, changing the mathematical parameters from (azimuth, zenith angle) to (azimuth, polar angle). This parameter transformation ensures that bins have equal area on the sphere, solving the sampling uniformity problem while maintaining computational feasibility through the use of pre-computed spherical binning tables.
Solution Approach 2:
The patent applies spherical geometry to the binning process by defining bins as equal-area regions on a sphere rather than cylindrical sectors. This spherical approach naturally accounts for the geometric relationship between angles and areas, ensuring uniform sampling across all angular ranges while preserving the simplicity of the binning operation through standardized spherical coordinate transformations.
2Quantity of substance
If coarser angular bins are used to accommodate typical node separation, then the data sampling requirements are reduced, but the resolution of image gathers deteriorates
Solution Approach 1:
By changing from cylindrical to spherical binning parameters, the patent achieves more efficient use of available data. The equal-area bins in spherical coordinates provide uniform angular resolution without requiring denser sampling, effectively decoupling the resolution from the node separation constraints and allowing coarser sampling to maintain the same resolution.
3Manufacturing precision
If equal area spherical binning is implemented, then the angular sampling uniformity is improved, but the computational complexity of the binning process increases
Solution Approach 1:
The patent performs binning table lookups and coordinate transformations in advance, storing pre-computed binning parameters and transformation matrices. This preliminary action eliminates the need for complex real-time calculations during the actual RTM imaging process, reducing computational complexity while maintaining the precision benefits of spherical binning.
4Speed
If conventional binning is used, then the processing speed is maintained, but the quality and amplitude behavior of image gathers are degraded due to sampling sensitivity
Solution Approach 1:
The spherical binning parameter transformation provides more stable and uniform sampling across all angular ranges, which improves the quality and amplitude behavior of image gathers. The equal-area bins ensure consistent representation of different angular components, reducing artifacts and improving the reliability of AVO and AVAZ analyses without significantly impacting processing speed due to efficient implementation.
Data Source
AI summary
Seismic exploration of an underground formation uses seismic excitations to probe the formation's properties such as reflectivity that can be imaged using reverse time migration. Using an equal area spherical binning at reflection points improves and simplifies RTM imaging together with adaptability to the data acquisition geometry, while overcoming drawbacks of conventional cylindrical binning.