Downgoing Wavelet Extraction from VSP Data
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Solution Overview
Problem
Existing methods for extracting downgoing wavelets and attenuation parameters from VSP data suffer from low accuracy due to the interdependence of wavelet extraction and attenuation parameter calculation, leading to inaccurate results.
Innovation Solution
A method and apparatus that involve picking up P-wave first arrival times, performing upgoing and downgoing P-waves separation, applying FFT, subtracting a downgoing wavelet log spectrum to correct the multi-trace P-wave log spectrum, and using the corrected parameters to extract accurate downgoing wavelets and attenuation parameters, including true amplitude recovery factor and Q factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate extraction of downgoing wavelets and attenuation parameters is performed using conventional methods, then the processing workflow is simple, but the accuracy of extracted parameters is low due to mutual interference between wavelet and parameter estimation
Solution Approach 1:
The patent segments the spectrum into multiple frequency bands and processes each band separately to extract downgoing wavelets and attenuation parameters. By dividing the complex spectrum into manageable segments and processing them independently, the method avoids mutual interference between wavelet and parameter estimation while maintaining workflow manageability through systematic segmentation of the frequency domain
Solution Approach 2:
The patent introduces an intermediary spectral analysis step that separates the downgoing wavelet characteristics from attenuation parameter characteristics in the frequency domain. This intermediary spectral processing acts as a mediator that decouples the previously intertwined estimation processes, allowing accurate extraction of both wavelets and parameters without direct mutual interference
2Measurement precision
If the downgoing wavelet is not properly isolated from the spectrum, then the processing is faster, but the attenuation parameters are affected by wavelet artifacts leading to inaccurate results
Solution Approach 1:
The patent extracts the downgoing wavelet spectrum from the total spectrum by isolating and removing wavelet-related frequency components. This extraction process separates the wavelet characteristics from the attenuation characteristics, ensuring that attenuation parameters are calculated without contamination from wavelet artifacts while maintaining processing efficiency through targeted spectral subtraction
Solution Approach 2:
The patent performs preliminary downgoing wavelet extraction and spectral correction before attenuation parameter calculation. By预先 removing the wavelet influence from the spectrum, the method ensures that subsequent attenuation parameter estimation is not affected by wavelet artifacts, thereby improving accuracy without significantly impacting overall processing efficiency
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 improves the accuracy of downgoing wavelet and attenuation parameter extraction by isolating the influence of the downgoing wavelet, ensuring the parameters converge within a preset range, thereby enhancing the precision of both wavelet and attenuation parameter calculations.
Implementation Method 1
performing a FFT on seismic data with a preset time window length starting from the P-wave first arrival time and cut from the downgoing P-wave data to obtain FFT transformed downgoing P-wave data
Data Source
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Figure 3(a)~3(c)
AI summary
A method for extracting a downgoing wavelet and attenuation parameters from VSP data, comprising: performing upgoing and downgoing P-waves separation processing on VSP data to obtain downgoing P-wave data; performing a FFT on seismic data with a preset time window length starting from the P-wave first arrival time and cut from the downgoing P-wave data to obtain FFT transformed downgoing P-wave data and a multi-trace downgoing P-wave log spectrum; subtracting a downgoing wavelet log spectrum from the multi-trace downgoing P-wave log spectrum to obtain a wavelet-corrected multi-trace downgoing P-wave log spectrum; performing, based on parameters of the wavelet-corrected multi-trace downgoing P-wave log spectrum, a correction and an inverse FFT on the FFT transformed downgoing P-wave data to obtain a downgoing wavelet; and obtaining attenuation parameters based on P-wave first arrival time and the parameters of the wavelet-corrected multi-trace downgoing P-wave log spectrum. The method can extract a downgoing wavelet and attenuation parameters with high accuracy. Also provided are an apparatus for extracting a downgoing wavelet and attenuation parameters from VSP data, a computer device, and a computer-readable storage medium.