Offset Vector Tile Gather Seismic Imaging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional 3D seismic surveys using common-offset vector (COV) binning face challenges in producing clear images of the subsurface due to artifacts caused by the footprint of seismic receiver cables, especially in dual-datum acquisition and mode-converted PS-wave data, which result in irregular subsurface illumination and migration distortions.
Innovation Solution
The method involves creating offset vector tile (OVT) gathers with time- and velocity-model dependent weighting and muting functions to ensure uniform illumination, adjusting the size of OVT gathers based on depth and offset, and muting outer seismic traces with a taper zone to suppress cable footprints in the 3D image, thereby improving reflection point distribution and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional COV binning is used for 3D seismic surveys, then single-fold datasets can be obtained with surface offset and azimuth preserved, but cable footprints and irregular subsurface illumination cause artifacts in the migrated image
Solution Approach 1:
The patent divides the seismic data processing into discrete offset vector tile (OVT) gathers, where each tile corresponds to a specific spatial region and offset range. This segmentation allows independent processing and illumination correction for each tile, enabling precise control over cable footprint suppression while maintaining overall image quality.
Solution Approach 2:
The patent applies local illumination corrections and weighting functions specific to each OVT gather based on its geometric characteristics, source-receiver configuration, and depth range. This local quality approach ensures that each tile is processed with optimal parameters tailored to its specific conditions, effectively suppressing cable footprints while preserving subsurface illumination uniformity.
2Adaptability or versatility
If COV binning is applied to dual-datum acquisition or mode-converted PS-wave data, then post-migration processing can be enhanced, but irregular subsurface illumination causes artifacts including acquisition footprints
Solution Approach 1:
The patent dynamically adjusts illumination correction parameters, weighting factors, and muting functions based on the specific wave type (P-wave, PS-wave), acquisition geometry (single-datum, dual-datum), and depth level. These parameter changes are computed for each OVT gather to match its specific characteristics, enabling effective processing of diverse data types while suppressing irregular illumination artifacts.
3Ease of manufacture
If standard OVT gathers are used without depth-dependent corrections, then processing is simpler, but uniform illumination cannot be achieved at all depth levels
Solution Approach 1:
The patent implements dynamic, depth-dependent OVT gather definitions where the gather size, offset range, and weighting functions are adjusted as a function of depth level. This dynamic approach allows the processing parameters to adapt to the changing geometric relationships and illumination conditions at different depths, achieving uniform illumination throughout the subsurface volume.
Data Source
AI summary
A method for using an offset vector tile gather to image a subsurface defines an offset vector tile gather by selecting a plurality of seismic traces from recorded seismic data. Each seismic trace in the offset vector tile includes reflections from subsurface reflectors and reflection points at depths below the surface of the subsurface. Each reflection point is in a given seismic trace, and each given seismic trace extends from a seismic source to a seismic receiver. The reflection points define an offset vector tile having a source line span and a receiver line span. The source line span is equal to or greater than a distance between adjacent seismic receiver lines, and the receiver line span is less than a distance between adjacent seismic source lines. The offset vector tile gather is used to produce a three dimensional image of the subsurface.