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Keywords: perturbation
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Proceedings Papers

Paper presented at the SEG/AAPG/SEPM First International Meeting for Applied Geoscience & Energy, September 26–October 1, 2021
Paper Number: SEG-2021-3594989
... fill strategy controls the gap size between samples. This approach has similar performance compared to the jittered sampling schemes in terms of the signal-to-noise ratio of reconstructed signals. However, a robustness test demonstrates that the two-stage scheme is more robust to perturbations...
Proceedings Papers

Paper presented at the SEG/AAPG/SEPM First International Meeting for Applied Geoscience & Energy, September 26–October 1, 2021
Paper Number: SEG-2021-3582313
.... Alternatively, joint full waveform inversion (JFWI) assumes a scale separation in the model space such that low wavenumbers can be recovered from both diving and reflected waves, in addition to high-wavenumber reflection impedance perturbations. In this work, we apply JFWI to 4D data to improve the estimation...
Proceedings Papers

Paper presented at the SEG/AAPG/SEPM First International Meeting for Applied Geoscience & Energy, September 26–October 1, 2021
Paper Number: SEG-2021-3581908
... scenarios, in particular at shallow water pose to simultaneously invert for the source signature and the depths and where the initial model built for FWI does not ac- medium parameters close to the source and receiver positions count for shallow medium perturbations that may be present. by directly...
Proceedings Papers

Paper presented at the SEG/AAPG/SEPM First International Meeting for Applied Geoscience & Energy, September 26–October 1, 2021
Paper Number: SEG-2021-3579336
... We consider the problem of solving the Helmholtz equation in 2D and 3D, where the velocity can be decomposed into a sum of two components: (i) the background velocity component that varies linearly with depth, and (ii) a smooth, compactly supported velocity perturbation. The integral equation...
Proceedings Papers

Paper presented at the SEG/AAPG/SEPM First International Meeting for Applied Geoscience & Energy, September 26–October 1, 2021
Paper Number: SEG-2021-3593872
... perturbation theory to the 2D magnitude of two sensitive kernels of first-arrival quasi-acoustic eikonal equation for VTI media from which stereotomography is comparable from 0 degree to 90 degree. the linear relation between the first-arrival The sensitivity analysis and a synthetic data example...
Proceedings Papers

Paper presented at the SEG/AAPG/SEPM First International Meeting for Applied Geoscience & Energy, September 26–October 1, 2021
Paper Number: SEG-2021-3594274
... point labeled data exploration geophysicist 10 perturbation waveform ssl horizon identification yellow arrow horizon point vat Seismic horizon identi cation using semi-supervised learning with virtual adversarial training Fu Wang Xinming Wu , and Huazhong Wang , Tongji University...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3399390
... expression for the radiation patterns produced Grechka, 2011; Maitra et al., 2018). Therefore, it is becoming by a scatterer that represents a perturbation in one of the stiff- increasingly important to build high-resolution orthorhombic ness coef cients or the density. To simplify the analysis, we velocity...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3421450
... the perturbation related to secondary sources as a modified source function. As the sources in the reflection-based EWI (REWI) are located in the subsurface, we are able to update the background model along the reflection wave path. We calculate the background model perturbation by a deconvolution process in each...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3428202
... synthetic tests on two variants of the Overthrust velocity model: a background model (Figure 1a), and a true model with positive and negative Gaussian perturbations (Figure 1b) that are added to the background model shown in Figure 1a. Distance (km) 0 0.5 1 1.5 2 2.5 3 3.5 Depth (km) 123 time (s) 0.4 0.2 0...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3428258
... of velocity perturbations and finding the global optimal solution, unlike local search methods that are based on gradient descent or ascent. The velocity updates are represented by hierarchical-scale basis functions. The goal is to find the updates that maximize the sum of the squares of the amplitudes...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3424929
... preconditioner upstream oil & gas iteration wavepath tomographic operator zero-offset wavepath dl 0 exploration geophysicist 10 full waveform inversion repositioning sin 2 facet depth-velocity coupling perturbation operator reflectivity sb 0 Accounting for the depth-velocity coupling...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3425157
... Direct envelope inversion (DEI) can be used to retrieve the low wave-number components of large-scale and strongcontrast velocity perturbations. However, envelope signals lose wave-field instantaneous phase (IP) information, which may result in the possibility of multiple solutions of envelope...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3427790
... In the conventional finite-frequency traveltime tomography, the traveltime Fréchet derivative is usually derived using the Born- or the Rytov approximation, which requires that the magnitude of velocity perturbations should be small enough to satisfy the weak-scattering assumption. For large...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3426646
... accurately model PS reflections with a virtual source, which is a function of the perturbations of Lam´e parameter μ and density. We use this quasi-elastic wave equation for least-squares reverse-time migration for PS reflections. The method iteratively updates the perturbations of elastic parameters...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-W06-04
.... initial model geophysics inversion zheng upstream oil & gas chinese academy waveform inversion exploration geophysicist 10 perturbation crosstalk fréchet derivative reservoir characterization reflection seg international exposition reflection wave gradient velocity model full waveform...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, September 15–20, 2019
Paper Number: SEG-2019-3215476
.... In this study, we develop a novel microseismic (extended) PS energy imaging condition that exhibits better sensitivity to isotropic and anisotropic elastic model perturbations compared to the existing imaging conditions. Numerical experiments demonstrate the sensitivity of microseismic TRI results to P- and S...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, September 15–20, 2019
Paper Number: SEG-2019-3215669
... perturbation sensitive kernel media joint inversion anisotropic parameter seg international exposition quasi-acoustic eikonal equation data component traveltime upstream oil & gas inversion geophysics vti quasi-acoustic eikonal equation vti media reservoir characterization stereotomography...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, September 15–20, 2019
Paper Number: SEG-2019-3216028
... ABSTRACT Full-waveform inversion (FWI) aims to update the long and short wavelengths of the perturbations, in which parameterization plays an important role in multiparameter updates. For the anisotropic inversion of a transversely isotropic medium with a vertical symmetry direction (VTI...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, September 15–20, 2019
Paper Number: SEG-2019-3216129
.... However, Born approximation is only valid for small model perturbations and has limited angle validity, while Kirchhoff approximation has no rigorous restriction about the jump in medium parameters across a given reflector and it also has a large regime of angle validity. For subsalt imaging...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, September 15–20, 2019
Paper Number: SEG-2019-3216208
... is used to perturb and update the wave impedance stochastic inversion. Finally, through the model test and analysis, the modeling method in this paper can well characterize the small-scale heterogeneity of the underground. The constructed likelihood function increases the stability of the inversion...

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