Mesoscopic Wave-Induced Fluid Flow Effect Extraction by Using Frequency-Dependent Prestack Waveform Inversion

Patchy saturation of gas and brine within the porous rock can induce significant attenuation and velocity dispersion effects, which in turn have a profound impact on seismic data. Thus, there should be a close relationship between dispersion and reservoir parameters, such as saturation, porosity, and permeability. Hence, using seismic data to determine dispersion information has been the subject of intensive research in recent years. It can help quantitatively predicting gas saturation and monitoring CO, sequestration, a key strategy for mitigation of global warming. Here, a frequency-dependent prestack waveform inversion workflow was proposed to extract the wave-induced fluid flow (WILT) effect from seismic data (WIFF prestack waveform inversion strategy). The proposed approach consists of three essential parts, comprising spectral decomposition, Q-compensated prestack waveform inversion, and frequency dependent prestack waveform inversion. First, l(1) norm constrained inverse spectral decomposition is exploited to provide time -frequency amplitude and phase spectra with high resolution and reliable accuracy. Then, constant-Q compensated prestack waveform inversion is used to generate relatively precise P- and S-wave velocities, density, and Frechet derivative tier the subsequent dispersion inversion. Finally, frequency-divided seismic data and the estimated parameters and Frechet derivative are used to invert the P-wave velocity dispersion. A comparison between the inversion results and band-limited rock physics analysis results shows that the proposed method can provide a quantitative inversion of the velocity dispersion to some extent. The proposed strategy provides a possibility for quantifying dispersion and further estimating gas saturation.

Automated summary

The study discusses the impact of gas and brine saturation in porous rocks on seismic data, emphasizing the importance of the relationship between dispersion and reservoir parameters. A proposed frequency-dependent prestack waveform inversion workflow can help in accurately extracting wave-induced fluid flow effects, leading to a quantitative inversion of velocity dispersion and potential estimation of gas saturation.