Seismic Velocity Model Correction via Anomaly Identification
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Solution Overview
Problem
Seismic imaging techniques often produce geologically implausible subsurface structures due to multiple velocity solutions and difficulties in correcting velocity models, especially in noisy conditions and complex geology, leading to inaccuracies in subsurface imaging.
Innovation Solution
A method involving the use of a graphical user interface, processor, and data storage to identify and correct anomalous features in seismic images by placing dip bars and masks to specify structural corrections, performing an inversion to update velocity models, and applying smoothing constraints to produce a more accurate subsurface image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If geophysical inversion techniques are used to flatten image gathers, then velocity model correction is attempted, but in noisy conditions and complex geology it becomes difficult to see events on prestack gathers and hard to modify the velocity model to make them flat
Solution Approach 1:
The method performs preliminary migration to generate an initial seismic image and identifies anomalous features before performing the inversion process. This preliminary imaging and anomaly identification prepares the data and guides subsequent velocity model corrections, making the inversion process more effective in noisy conditions and complex geology.
2Manufacturing precision
If velocity model changes are made to flatten gathers, then image quality may improve, but a range of velocity models can flatten gathers while producing significantly different structure in the image
Solution Approach 1:
The method uses an iterative feedback process where the seismic image is continuously updated and re-examined after each velocity model modification. The inversion process compares the updated image against expected geological structures and adjusts the velocity model accordingly, ensuring that flattening does not compromise structural accuracy. This feedback loop resolves the ambiguity by selecting the velocity model that produces both flat gathers and geologically plausible structures.
3Productivity
If standard inversion processes are used, then velocity models are generated, but they may produce geologically implausible seismic images with crossing beds and complex artifacts
Solution Approach 1:
The method performs preliminary migration and anomaly identification before the main inversion process, preparing the data in a way that guides the inversion toward geologically plausible solutions. This preliminary action prevents the generation of implausible structures by establishing correct geological frameworks beforehand.
Solution Approach 2:
The iterative feedback process continuously evaluates whether the generated velocity model produces geologically plausible structures. If crossing beds or artifacts are detected, the inversion process adjusts the velocity model to eliminate these anomalies while maintaining imaging efficiency.
Data Source
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AI summary
A method of modifying a seismic image of a subsurface region includes identifying a location within the seismic image that includes a distortion, indicating a structural change associated with the distortion, that is selected to at least partially correct for the distortion, identifying a region causing the distortion in which corrections to a velocity model corresponding to the seismic image are to be applied, performing an inversion for the region in accordance with the indicated structural change, updating the velocity model on the basis of the inversion, and producing a modified seismic image on the basis of the updated velocity model.