Subsurface Velocity Model Accuracy via Directional Sub-Wave Processing
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Solution Overview
Problem
The accuracy of the velocity model of the subsurface medium obtained using existing seismic data processing methods needs to be improved for better imaging quality of seismic data.
Innovation Solution
The method involves acquiring seismic data by an ocean bottom node using a monopole source, determining a dipole source and a zero-phase monopole source, combining them to form a directional sub-wave, exchanging the ocean bottom node and shot point positions, and using the directional sub-wave to generate seismic synthetic data. This data, along with the up going wavefield of the seismic data, is used to determine a target velocity model that characterizes the propagation velocity of seismic waves in the subsurface medium.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a monopole source is excited at a shot point and seismic data is acquired using OBN, then seismic data can be collected, but the accuracy of the velocity model obtained by the full waveform inversion algorithm needs to be further improved
Solution Approach 1:
The patent segments the monopole source wavefield into two distinct components: a dipole source component (obtained by taking the first derivative of the monopole source with respect to vertical direction) and a zero-phase monopole source component (obtained by taking the second derivative with respect to time). This segmentation allows separate processing and inversion of different wavefield characteristics, thereby improving velocity model accuracy
Solution Approach 2:
The patent transforms the original monopole source parameters into derivative parameters - specifically, computing the first derivative with respect to vertical direction to obtain dipole source characteristics, and the second derivative with respect to time to obtain zero-phase monopole source characteristics. These parameter transformations enable more accurate characterization of seismic wave propagation
Data Source
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AI summary
A method for determining velocity of a subsurface medium includes: acquiring, by an ocean bottom node, seismic data generated by exciting a monopole source at a shot point (101); determining a dipole source and a zero-phase monopole source according to the monopole source, and combining the dipole source and the zero-phase monopole source to obtain a directional sub-wave (102); exchanging the position of the ocean bottom node with the position of the shot point and, acquiring, by the exchanged node, seismic synthetic data generated by exciting the directional sub-wave at the exchanged shot point (103); and determining a target velocity model according to an up going wavefield of the seismic data and the seismic synthetic data (104). By processing the monopole source and obtaining the directional sub-wave having a directional feature, acquiring the seismic synthetic data generated by exciting the directional sub-wave at the shot point, and determining the velocity model by the seismic synthetic data and an up going wavefield of the seismic data, the precision of the velocity model is improved. Further provided are an apparatus for determining the velocity of a subsurface medium, an electronic device, a computer-readable storage medium, and a program product.