A time-frequency domain full waveform inversion method and device using a normalized seismic source

Abstract

The invention discloses a time-frequency domain full-waveform inversion method and device using a normalized seismic source. The seismic source is a plurality of single-frequency signals extracted from known wavelets and the amplitudes are normalized, which is completed in the time domain. The wave field simulation of multiple normalized single-frequency seismic sources extracted; and the phase-sensitive detection method is used to decouple the forward wave field and the reverse wave field respectively, so as to obtain the amplitude and phase information of the wave field through decoupling , in order to eliminate the limitation of each frequency amplitude by the conventional band-limited wavelet amplitude spectrum in the inversion process, and then calculate the gradient of the velocity field model parameters according to the amplitude and phase information of the wave field and the gradient calculation expression, which is conducive to obtaining accurate The update direction of the velocity field model parameters, so as to achieve the purpose of simultaneous inversion of multiple frequencies in the inversion. The invention can weaken the limitation of the single-frequency signal amplitude by the wavelet amplitude spectrum in the conventional inversion, eliminate the wavelet effect in the inversion, realize the inversion result of spectrum whitening, and finally obtain the high-precision inversion result.

Description

technical field [0001] The invention relates to a time-frequency domain full waveform inversion method and device using a normalized seismic source, and belongs to the technical field of seismic exploration velocity modeling. Background technique [0002] As oil exploration shifts to deep and ultra-deep layers, high-precision imaging of steep and complex structures in deep target layers has become an imminent bottleneck restricting oil exploration and development. Velocity modeling is the soul of complex structural imaging, and traditional velocity modeling techniques such as velocity tomography inversion have achieved great success in the past few decades, but they can no longer meet the needs of high-resolution seismic imaging. Therefore, it is urgent to develop a new generation of velocity modeling technology to meet the needs of imaging complex structures. [0003] At present, full waveform inversion (Full Waveform Inversion, FWI) is recognized as the most potential new...

AI Technical Summary

Problems solved by technology

However, due to the needs of data simulation, the frequency contained in the wavelet has a certain amplitude distribution, that is, only the frequency update near the main frequency is dominant, and the update of more low-frequency information cannot be guaranteed; at the same time, it is impossible to calculate the gradient. Decoupling and normalizing the frequency features, so there is a wavelet effect in the full waveform inversion, and there will be a phenomenon of wrong update at the structural interface, which reduces the inversion accuracy to a certain extent; even if the multi-scale method is used, this subwave Wave effects also accompanies the entire inversion, leading to over-updating at the high-contrast boundaries of structures

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