Method and device for obtaining frequency attenuation gradient of seismic data

Abstract

The invention provides a method and device for obtaining the frequency attenuation gradient of seismic data. The method for obtaining the frequency attenuation gradient of the seismic data comprises the steps that an amplitude spectrum of a time-frequency domain of the target three-dimensional seismic data is calculated through a time-frequency three-parameter wavelet transform method; high-frequency-band data of the amplitude spectrum of each preset time sampling point are extracted; curve fitting calculation is conducted on the high-frequency-band data through a nonlinear curve fitting method based on the Nelde-Mead simplex algorithm, so that an exponential attenuation coefficient array formed by exponential attenuation coefficients corresponding to the preset time sampling points is obtained; background attenuation of the exponential attenuation coefficient array is removed, so that a frequency attenuation gradient array is obtained.

Description

technical field [0001] The invention relates to the field of exploration geophysics, more specifically, to a method and device for obtaining the frequency attenuation gradient of seismic data. Background technique [0002] The attenuation of seismic waves has a certain relationship with the oil-gas content of sandstones. When seismic waves pass through oil-gas-bearing sandstones, the energy will undergo obvious high-frequency attenuation, that is, the energy in the high-frequency band of the amplitude spectrum will obviously attenuate. In order to effectively utilize high-frequency attenuation information, in the prior art, the degree of frequency attenuation is characterized by calculating the exponential attenuation coefficient of the high-frequency amplitude spectrum of the signal, that is, the frequency attenuation gradient analysis technique, wherein the frequency range of the high-frequency amplitude spectrum Refers to the frequency corresponding to the maximum amplitu...

AI Technical Summary

Problems solved by technology

However, the Image module of EP-Tech software has certain defects because it uses the three-parameter wavelet transform method to calculate the amplitude spectrum in the time-frequency domain: the amplitude spectrum in the time-frequency domain based on the conventional continuous wavelet transform uses the Time-scale information conversion, and in this conversion process, each scale corresponds not to a frequency, but to a frequency band, resulting in energy overlap, which is more serious at high frequencies, resulting in Attenuation of high-frequency amplitude spectrum energy

Although the Image module of EP-Tech software uses three-parameter wavelet, compared with the conventional continuous wavelet transform, it only improves the wavelet function, while the core algorithm - continuous wavelet transform remains unchanged, that is, there are still high The energy attenuation phenomenon of the frequency band amplitude spectrum, the attenuation is not caused by oil and gas reservoirs, but the attenuation caused by continuous wavelet transform, which will affect the reliability of oil and gas reservoir prediction

In addition, the Image module of EP-Tech software uses a two-point linear fitting method to calculate the attenuation coefficient of the high-frequency amplitude spectrum, and its calculation accuracy needs to be improved

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