5D Angle-Domain Common-Image Gathers for Subsurface Imaging
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Solution Overview
Problem
Current seismic imaging techniques face challenges in obtaining high-resolution subsurface information from subterranean regions, particularly in borehole seismic data, due to noise and limited angular coverage, which affects the accuracy of reservoir analysis and drilling decisions.
Innovation Solution
The method generates five-dimensional angle-domain common-image gathers (ADCIG) from 3D vertical seismic profiling (VSP) data using the Kirchhoff integral method, computing four angle attributes (reflection-angle, azimuth-angle, dip-angle, and dip-azimuth-angle) to enhance structure imaging and rock property estimation, while infilling travel time shadow zones and migrating mode-converted energy in the time domain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional seismic imaging techniques are used, then the imaging process is simpler, but the resolution and accuracy of subsurface information is insufficient
Solution Approach 1:
The patent transitions from conventional 3D seismic imaging to 5D angle-domain common-image gathers (ADCIG) by adding two angular dimensions (incidence angle and azimuth angle). This dimensional expansion enables precise characterization of subsurface properties by analyzing seismic reflections from multiple angles, directly improving measurement precision while systematically managing the increased complexity through structured data organization.
Solution Approach 2:
The patent transforms seismic data by computing four angle attributes (incidence angle, azimuth angle, dip angle, and azimuth of dip angle) for each image point. This parameter transformation converts conventional seismic attributes into angular domain parameters, enabling more accurate rock property estimation and reservoir characterization through angle-dependent analysis.
2Reliability
If noise is present in borehole seismic data, then data acquisition is easier, but the accuracy of reservoir analysis deteriorates
Solution Approach 1:
The patent applies local quality enhancement by computing angle-specific attributes for each image point independently. By analyzing seismic reflections at different incidence and azimuth angles separately, the method can identify and emphasize reliable signal components while suppressing noise that does not exhibit consistent angular patterns, thereby improving reservoir analysis accuracy in noisy borehole seismic data.
Solution Approach 2:
The patent implements feedback through iterative angle-domain analysis where the computed ADCIGs are used to update the understanding of subsurface properties. The angular attributes provide feedback on the consistency and reliability of seismic reflections, allowing for noise filtering and enhancement of genuine subsurface signals through multiple analysis passes.
3Measurement precision
If angular coverage is limited, then data acquisition is simpler, but the quality of structure imaging deteriorates
Solution Approach 1:
The patent compensates for limited physical angular coverage by introducing the angle domain as an explicit analysis dimension. Even with limited source-receiver geometries, the computation of 5D ADCIGs with four angle attributes per image point creates a comprehensive angular representation, effectively synthesizing full angular coverage through mathematical transformation of the acquired data.
Data Source
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AI summary
Example computer-implemented method, computer-readable media, and computer system are described for generating subterranean imaging data based on initial isotropic and/or anisotropic velocity models for the vertical seismic profile (VSP) data and stored ocean bottom sensor (OBS) data. In some aspects, VSP data and OBS data of a subterranean region are received. Angle attributes for each image point are computed to image primary reflection and free surface multiples of the received VSP data and OBS data, respectively. Angle-domain common-image gathers (ADCIG) are generated according to a ray-equation method based on the angle attributes computed based on the received VSP data and OBS data, respectively. The ADCIG are further post-processed.