We estimate the elastic properties of marine sediments beneath the seabed by means of high-resolution velocity analysis and 1D elastic full-waveform inversion (FWI) performed on 2D seismic data of a well-site survey (WSS). A high-resolution velocity functional is employed to exploit the broad frequency band of the WSS data and to derive the compressional velocity field with a high degree of accuracy. The estimated velocity field is then used as a priori information in the 1D elastic FWI that is solved by making use of genetic algorithms as optimization method. We consider two error functions: the first uses the entire waveform to compute the misfit between modelled and observed seismograms; the second considers the envelope of the seismograms thus relaxing the requirement of an exact estimation of the wavelet phase. The very similar velocities and density depth trends derived in the two FWI tests indicate the reliability of the predicted subsurface model. Moreover, the FWI and the high-resolution velocity analysis yield comparable velocity profiles, although with different resolution.
Characterization of Shallow Marine Sediments by Means of High Resolution Velocity Analysis and Stochastic 1D FWI
ALEARDI, MATTIA;TOGNARELLI, ANDREA;MAZZOTTI, ALFREDO
2015-01-01
Abstract
We estimate the elastic properties of marine sediments beneath the seabed by means of high-resolution velocity analysis and 1D elastic full-waveform inversion (FWI) performed on 2D seismic data of a well-site survey (WSS). A high-resolution velocity functional is employed to exploit the broad frequency band of the WSS data and to derive the compressional velocity field with a high degree of accuracy. The estimated velocity field is then used as a priori information in the 1D elastic FWI that is solved by making use of genetic algorithms as optimization method. We consider two error functions: the first uses the entire waveform to compute the misfit between modelled and observed seismograms; the second considers the envelope of the seismograms thus relaxing the requirement of an exact estimation of the wavelet phase. The very similar velocities and density depth trends derived in the two FWI tests indicate the reliability of the predicted subsurface model. Moreover, the FWI and the high-resolution velocity analysis yield comparable velocity profiles, although with different resolution.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
