Seismic Velocity Model for Near-Surface Shingles
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Solution Overview
Problem
Current seismic imaging methods fail to accurately model subsurface structures due to the presence of high-velocity stringers or shingles in the near-surface weathered layer, leading to velocity inversions and inaccurate depth models.
Innovation Solution
A method involving the identification of arrival times corresponding to a weathered layer velocity gradient, generation of a velocity model, and time adjustment of seismic data using this model, which allows for improved seismic imaging by accounting for the effects of shingles in the near-surface layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional seismic imaging methods are used, then processing is simple and fast, but imaging accuracy deteriorates due to velocity inversions from high-velocity stringers
Solution Approach 1:
The weathered layer is segmented into multiple sub-layers based on velocity gradients, with each sub-layer assigned a specific velocity value. This segmentation allows the complex velocity structure with inversions to be modeled as a series of simpler, manageable layers, resolving the contradiction by making the complex velocity model computationally tractable while maintaining imaging accuracy.
Solution Approach 2:
The method changes the velocity parameter from a continuous gradient to discrete velocity values assigned to each sub-layer. By transforming the continuous velocity field into discrete parameters, the method maintains accuracy in representing velocity inversions while simplifying the computational complexity of the imaging process.
2Measurement precision
If high-velocity stringers are treated as noise and excluded, then velocity model simplicity is maintained, but depth model accuracy deteriorates
Solution Approach 1:
The method converts the harmful effect of high-velocity stringers (which cause velocity inversions and imaging errors) into a beneficial feature by explicitly modeling them as distinct sub-layers with higher velocity values. Instead of treating stringers as noise to be eliminated, the invention incorporates them into the velocity model, transforming the problem into a solution that improves depth imaging accuracy.
Solution Approach 2:
The velocity model acts as an intermediary that mediates between the raw seismic data containing shingle noise and the final depth image. By introducing a multi-layer velocity model that explicitly accounts for high-velocity stringers, the method filters out the harmful effects of shingling while preserving the useful information for accurate depth imaging.
3Reliability
If continuous velocity gradient is assumed, then model simplicity is maintained, but representation of velocity inversions deteriorates
Solution Approach 1:
The continuous velocity gradient is segmented into discrete sub-layers, each with a representative velocity value. This segmentation enables the velocity model to reliably represent velocity inversions (where velocity decreases with depth) by allowing individual sub-layers to have higher velocities than underlying layers, while keeping the overall model structure simple and computationally manageable.
Solution Approach 2:
The method changes the velocity parameter from a continuous function of depth to discrete velocity values assigned to each sub-layer. This parameter transformation enables reliable representation of velocity inversions by allowing non-monotonic velocity variations across layers, while maintaining model simplicity through the use of discrete, manageable parameters.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances seismic data processing by accurately modeling the subsurface, reducing noise from shingles and improving the accuracy of depth models, enabling better subsurface imaging.
Implementation Method 1
seismic energy is detected by each of the plurality of seismic sensors in response to energy imparted into the areas of the subsurface by the seismic energy source
Data Source
AI summary
A method for weathered layer correction of seismic data includes identifying arrival times in the seismic data corresponding to a weathered layer velocity gradient. A velocity model of the weathered layer is generated using the arrival times. The seismic data are time adjusted using the velocity model.