Searched for: +
(1 - 20 of 100)

Pages

document
Wapenaar, C.P.A. (author), Brackenhoff, J. (author), De Ridder, S. (author), Slob, E.C. (author), Snieder, R. (author)
Green’s functions and propagator matrices are both solutions of the wave equation, but whereas Green’s functions obey a causality condition in time (G = 0 for t < 0), propagator matrices obey a boundary condition in space. Marchenko-type focusing functions focus a wave field in space at zero time. We discuss the mutual relations between Green...
conference paper 2023
document
Shoja, Aydin (author), van der Neut, J.R. (author), Wapenaar, C.P.A. (author)
Least-squares reverse time migration (LSRTM) is a common imaging technique that geophysicists have been using to obtain high-resolution images. Nevertheless, the high computational cost shifted the focus of researchers to the target-oriented approach. In this approach, by limiting the computational grid to a relatively smaller region, the...
conference paper 2022
document
Wapenaar, C.P.A. (author), de Ridder, Sjoerd (author), Dukalski, Marcin (author), Reinicke, Christian (author)
Standard Marchenko redatuming and imaging schemes neglect evanescent waves and are based on the assumption that decomposition into downgoing and upgoing waves is possible in the subsurface. Recently we have shown that propagator matrices, which circumvent these assumptions, can be expressed in terms of Marchenko focusing functions. In this paper...
conference paper 2022
document
Dukalski, Marcin (author), Reinicke, Christian (author), Wapenaar, C.P.A. (author)
Marchenko equation-based methods promise data-driven, true-amplitude internal multiple elimination. The method is exact in 1-D acoustic media, however it needs to be expanded to account for the presence of 2- and 3-D elastodynamic wave-field phenomena, such as compressional (P) to shear (S) mode conversions, total reflections or evanescent waves...
conference paper 2022
document
Meles, G.A. (author), Reinicke, Christian (author), Dukalski, M (author), Wapenaar, C.P.A. (author)
Marchenko redatuming retrieves Green’s functions inside an unknown medium, by solving a set of coupled Marchenko equations, which are derived from an under-determined system of equation and two temporal truncations. To constrain the problem, two assumptions are made, which hold reasonably well for acoustic, but not for elastodynamic waves. First...
conference paper 2022
document
van der Neut, J.R. (author), Brackenhoff, J. (author), Meles, Giovanni Angelo (author), Slob, E.C. (author), Wapenaar, C.P.A. (author)
Green’s functions in an unknown elastic layered medium can be retrieved from single-sided reflection data by solving a Marchenko equation. This methodology requires a priori knowledge of all forward-scattered (non-converted and converted) waveforms. Moreover, the medium should satisfy stringent monotonicity conditions, which are often not met in...
conference paper 2022
document
Dukalski, M (author), Reinicke, Christian (author), Wapenaar, C.P.A. (author)
The presence of evanescent modes and their impact on the Marchenko method has been until very recently a topic that received little attention. In this contribution we link the concept of the transfer matrix to the fields usually associated with the Marchenko method. Using that formalism, we introduce the concept of a path reversal - a...
conference paper 2022
document
Al Hasani, M.M.K. (author), Drijkoningen, G.G. (author), Wapenaar, C.P.A. (author)
In a surface-seismic setting, Distributed Acoustic Sensing (DAS) is still not a widely adopted method for near-surface characterisation, especially for reflection seismic imaging, despite the dense spatial sampling it provides over long distances. This is mainly due to the decreased broadside sensitivity that DAS suffers from when buried...
conference paper 2022
document
van der Neut, J.R. (author), Brackenhoff, J. (author), Meles, G. (author), Zhang, L. (author), Slob, E.C. (author), Wapenaar, C.P.A. (author)
Green’s functions in an unknown medium can be retrieved from single-sided reflection data by solving a multidimensional Marchenko equation. This methodology requires knowledge of the direct wavefield throughout the medium, which should include forward-scattered waveforms. In practice, the direct field is often computed in a smooth background...
conference paper 2021
document
Almobarak, M. (author), van IJsseldijk, J.E. (author), Wapenaar, C.P.A. (author)
Seismic imaging is often used to interpret subsurface formations. However, images obtained by conventional methods are contaminated with internal multiples. The Marchenko method provides the means to obtain multiple-free subsurface images. Due to the high computational cost of the conventional point-source Marchenko imaging method, the less...
conference paper 2021
document
Pijnenburg, R. (author), Laumann, S.J. (author), Wessels, R. (author), Maat, G. Ter (author), Armstrong, L.S. (author), Vardon, P.J. (author), Bruhn, D.F. (author), Barnhoorn, A. (author), Wapenaar, C.P.A. (author)
The European Plate Observing System - Netherlands (EPOS-NL) is the Dutch research infrastructure for solid Earth sciences. EPOS-NL is a cluster of large-scale geophysical facilities for research on georesources and geohazards. It is a partnership between Delft University of Technology (TU Delft), the Royal Netherlands Meteorological Institute...
conference paper 2021
document
Meles, G.A. (author), Zhang, L. (author), Thorbecke, J.W. (author), Wapenaar, C.P.A. (author), Slob, E.C. (author)
Seismic images provided by reverse time migration can be contaminated by artefacts associated with the migration of multiples.<br/><br/>Multiples can corrupt seismic images, producing both false positives, i.e. by focusing energy at unphysical interfaces, and false negatives, i.e. by destructively interfering with primaries. Multiple-related...
conference paper 2020
document
Wapenaar, C.P.A. (author), van IJsseldijk, J.E. (author)
Time-lapse seismic monitoring aims at resolving changes in a producing reservoir from changes in the reflection response. When the changes in the reservoir are very small, the changes in the seismic response can become too small to be reliably detected. In theory, multiple reflections can be used to improve the detectability of traveltime...
conference paper 2020
document
Wapenaar, C.P.A. (author)
Current Marchenko algorithms require up/down separation, and solving the Marchenko equation enables one to retrieve the up/down components of the Green's function. We propose an iterative scheme to relax the need for up/down separation for focusing. By presenting a visual tour, we show how to retrieve the Green's function in the subsurface at...
conference paper 2020
document
van IJsseldijk, J.E. (author), Wapenaar, C.P.A. (author)
The Marchenko method retrieves the responses to virtual sources in the subsurface, accounting for all orders of multiples. The method is based on two integral representations for focusing and Green’s functions. In discretized form these integrals are represented by finite summations over the acquisition geometry. Consequently, the method...
conference paper 2020
document
Shoja, Aydin (author), Meles, G.A. (author), Wapenaar, C.P.A. (author)
The Hessian matrix plays an important role in correct interpretation of the multiple scattered wave fields inside the FWI frame work. Due to the high computational costs, the computation of the Hessian matrix is not feasible. Consequently, FWI produces overburden related artifacts inside the target zone model, due to the lack of the exact...
conference paper 2020
document
Wapenaar, C.P.A. (author), Staring, M. (author), Brackenhoff, J.A. (author), Zhang, L. (author), Thorbecke, J.W. (author), Slob, E.C. (author)
Since the introduction of the Marchenko method in geophysics, many variants have been developed. Using a compact unified notation, we review redatuming by multidimensional deconvolution and by double focusing, virtual seismology, double dereverberation and transmission-compensated Marchenko multiple elimination, and discuss the underlying...
conference paper 2020
document
Reinicke Urruticoechea, C. (author), Dukalski, M.S. (author), Wapenaar, C.P.A. (author)
Marchenko methods aim to remove all overburden-related internal multiples. The acoustic and elastodynamic formulations observe identical equations, but different physics. The elastodynamic case highlights that the Marchenko method only handles overburden-generated reflections, i.e. forward-scattered transmitted waves (and so-called fast...
conference paper 2020
document
Staring, M. (author), Zhang, L. (author), Thorbecke, J.W. (author), Wapenaar, C.P.A. (author)
We have seen many developments in Marchenko equation-based methods for internal multiple attenuation in the past years. Starting from a wave-equation based method that required a smooth velocity model, there are now Marchenko equation-based methods that do not require any model information or user-input. In principle, these methods accurately...
conference paper 2020
document
Brackenhoff, J.A. (author), van IJsseldijk, J.E. (author), Wapenaar, C.P.A. (author)
We consider reflection data that have been subsampled by 70% and use Point-Spread-Functions to reconstruct the original data. The subsampled, original and reconstructed reflection data are used to image the medium of interest with the Marchenko method. The image obtained using the subsampled data shows artifacts caused by internal multiples,...
conference paper 2020
Searched for: +
(1 - 20 of 100)

Pages