2-D acoustic Laplace-domain waveform inversion of marine field data

Abstract

SUMMARY The Laplace‐domain full waveform inversion method can build a macroscale subsurface velocity model that can be used as an accurate initial model for a conventional full waveform inversion. The acoustic Laplace‐domain inversion produced is promising for marine field data examples. Although applying an acoustic inversion method to the field data generally requires several pre‐processing steps, pre‐processing for the Laplace‐domain inversion has not been explained in detail. We provide a detailed explanation of how to apply the Laplace‐domain waveform inversion to field data through numerical tests with Gulf of Mexico data sets. The pre‐processing includes bandpass filtering, muting of the noise before the first arrival, and extraction of the water depth. We choose the range and the interval between the Laplace damping constants empirically by applying a threshold value to the damped time traces and the Laplace‐domain wavefields. The observed data are transformed to the Laplace domain using the selected damping; this method yielded a long‐wavelength inversion result. The damping constant and the maximum offset affect the penetration depth of the inversion result. The maximum recording time is important for a stable Laplace‐transformation and affects the inversion result; however, the latter effect is not significant.

Seismic Random Noise Attenuation in the Laplace Domain Using Singular Value Decomposition

“…On the other hand, there is no meaningful difference between the inversion results from the noisy and denoised data (Figs. 10c and d); however, by denoising, the initial cost function value after source estimation [34] is reduced to 94.9 % of that of the noisy data, and the error after 100 iterations is reduced to 22.6 % (Fig. 11).…”

“…These SNRs are higher than those of the time-domain seismogram because they are dominated by large-amplitude near-offset signals. Large-offset signals are important for recovering deep structures in Laplace-domain inversions [34]; however, the overall SNR cannot reflect noise-contaminated large-offset signals. Fig.…”

Imaging the P‐Wave Velocity Structure of Arctic Subsea Permafrost Using Laplace‐Domain Full‐Waveform Inversion

“…The raw seismic data, which were acquired on the continental shelf of the CBS by the onboard seismic system of the IBRV ARAON, were preprocessed using the approach of Ha et al. (2012). The preprocessing procedure for the raw seismic data includes noise removal processing and the Laplace‐transformed from time series.…”

Multiscale Direct Envelope Inversion: Algorithm and Methodology for Application to the Salt Structure Inversion

“…Therefore, it is also an effective method in taking measures to mitigate nonlinearity in the FWI. Constructing a more convex objective function is a widely used method: The Laplace domain inversion and Laplace‐Fourier domain use the zero‐frequency and low‐frequency components of the damped wavefield to obtain the long‐wavelength components of the subsurface (Cha & Shin, ; Ha et al, , ; Ha & Shin, ; Kwon et al, ; Shin & Cha, , ; Shin et al, ). Similar to the layer stripping and time window methods (Y. H. Wang & Rao, ; Yoon et al, ), FWI uses the time‐damping wavefield to invert the velocity model in a shallow‐to‐deep manner to reduce the risk of the inversion falling into a local minimum (Chen et al, , ; Choi & Alkhalifah, ).…”