be retrieved from reflection data and a background model. Initially, the focusing function was defined such that it focuses inside the medium of interest as a point in time and in space (e.g. Wapenaar et al., 2014). The focusing property is used to retrieve the up- and downgoing Green’s functions associated to a virtual point source or receiver inside the medium. Subsequently, the retrieved Green’s functions are used to compute an image. Meles et al. (2017) introduced a new focusing function that focuses as a plane wave inside the medium. The new focusing function allows to retrieve medium responses associated to

virtual plane wave sources or receivers inside the medium. Hence, imaging based on areal-sources as suggested by Rietveld et al. (1992) becomes possible including the benefits of the Marchenko method. In the following we compare Marchenko imaging using point and plane wave focusing.","","en","conference paper","EAGE","","","","","Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.","","2018-12-15","","","","","","" "uuid:459fdf96-c15d-45a3-aa93-89c03b17e985","http://resolver.tudelft.nl/uuid:459fdf96-c15d-45a3-aa93-89c03b17e985","Implementation of the marchenko method","Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2017","The Marchenko method makes it possible to compute subsurface-to-surface Green's functions from reflection measurements at the surface. Applications of the Marchenko method have already been discussed in many papers, but its implementation aspects have not yet been discussed in detail. Solving the Marchenko equation is an inverse problem. The Marchenko method computes a solution of the Marchenko equation by an (adaptive) iterative scheme or by a direct inversion. We have evaluated the iterative implementation based on a Neumann series, which is considered to be the conventional scheme. At each iteration of this scheme, a convolution in time and an integration in space are performed between a so-called focusing (update) function and the reflection response. In addition, by applying a time window, one obtains an update, which becomes the input for the next iteration. In each iteration, upgoing and downgoing focusing functions are updated with these terms. After convergence of the scheme, the resulting upgoing and downgoing focusing functions are used to compute the upgoing and downgoing Green's functions with a virtual-source position in the subsurface and receivers at the surface. We have evaluated this algorithm in detail and developed an implementation that reproduces our examples. The software fits into the Seismic Unix software suite of the Colorado School of Mines.","","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:048b6e7c-398b-42ee-8d9b-53c693cc3023","http://resolver.tudelft.nl/uuid:048b6e7c-398b-42ee-8d9b-53c693cc3023","A new approach to separate seismic time-lapse time shifts in the reservoir and overburden","Liu, Y. (Norwegian University of Science and Technology); Landrø, Martin (Norwegian University of Science and Technology); Arntsen, Børge (Norwegian University of Science and Technology); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2017","For a robust way of estimating time shifts near horizontal boreholes, we have developed a method for separating the reflection responses above and below a horizontal borehole. Together with the surface reflection data, the method uses the direct arrivals from borehole data in the Marchenko method. The first step is to retrieve the focusing functions and the updown wavefields at the borehole level using an iterative Marchenko scheme. The second step is to solve two linear equations using a least-squares minimizing method for the two desired reflection responses. Then, the time shifts that are directly linked to the changes on either side of the borehole are calculated using a standard crosscorrelation technique. The method is applied with good results to synthetic 2D pressure data from the North Sea. One example uses purely artificial velocity changes (negative above the borehole and positive below), and the other example uses more realistic changes based on well logs. In the 2D case with an adequate survey coverage at the surface, the method is completely data driven. In the 3D case inwhich there is a limited number of horizontal wells, a kinematic correct velocity model is needed, but only for the volume between the surface and the borehole. Possible error factors related to the Marchenko scheme, such as an inaccurate source wavelet, imperfect surface multiples removal, and medium with loss are not included in this study.","","en","journal article","","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:0ec47f8d-06ec-4d2a-8cb6-2532fb2cd38c","http://resolver.tudelft.nl/uuid:0ec47f8d-06ec-4d2a-8cb6-2532fb2cd38c","A Marchenko equation for acoustic inverse source problems","van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Johnson, Jami L. (University of Auckland); van Wijk, K. (University of Auckland); Singh, S. (University of Edinburgh); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","From acoustics to medical imaging and seismology, one strives to make inferences about the structure of complex media from acoustic wave observations. This study proposes a solution that is derived from the multidimensional Marchenko equation, to learn about the acoustic source distribution inside a volume, given a set of observations outside the volume. Traditionally, this problem has been solved by backpropagation of the recorded signals. However, to achieve accurate results through backpropagation, a detailed model of the medium should be known and observations should be collected along a boundary that completely encloses the volume of excitation. In practice, these requirements are often not fulfilled and artifacts can emerge, especially in the presence of strong contrasts in the medium. On the contrary, the proposed methodology can be applied with a single observation boundary only, without the need of a detailed model. In order to achieve this, additional multi-offset ultrasound reflection data must be acquired at the observation boundary. The methodology is illustrated with one-dimensional synthetics of a photoacoustic imaging experiment. A distribution of simultaneously acting sources is recovered in the presence of sharp density perturbations both below and above the embedded sources, which result in significant scattering that complicates the use of conventional methods.","","en","journal article","","","","","","","","2017-12-31","","","Applied Geophysics and Petrophysics","","","" "uuid:61610d9a-db9e-44ef-aa18-a4b178fb620c","http://resolver.tudelft.nl/uuid:61610d9a-db9e-44ef-aa18-a4b178fb620c","Up-Down Wavefields Reconstruction in Boreholes Using Single-Component Data","Liu, Y. (Norwegian University of Science and Technology); Arntsen, B (Norwegian University of Science and Technology); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","A standard procedure in processing vertical seismic profile (VSP) data is the separation of up-and downgoing wavefields. We show that the up-down wavefields in boreholes can be reconstructed using only singlecomponent borehole data, given that a full set of surface reflection data is also available. No medium parameters are required. The method is wave-equation based for a general inhomogeneous lossless medium with moderately curved interfaces. It relies on a focusing wavefield from the Marchenko method, which gives the recipe for finding this wavefield that satisfies certain focusing conditions in a reference medium. The up-down wavefields are then reconstructed at borehole positions using this focusing wavefields and the surface reflection response. We show that the method is applicable to boreholes with any general orientation. The requirement is that the source positions in the surface data are regularized to be the same as those in the borehole data, and that source deconvolution and surface multiple removal are applied for the surface data. Numerical results from a field in the North Sea are shown, and three different borehole geometries (horizontal, deviated and vertical) are tested. The result shows that the reconstructed up-down wavefields agree well with those by conventional separation methods.","","en","conference paper","EAGE","","","","","","","2018-06-01","","","Applied Geophysics and Petrophysics","","","" "uuid:7226c2a4-f516-4b3c-aaed-1d2ea7da0ab2","http://resolver.tudelft.nl/uuid:7226c2a4-f516-4b3c-aaed-1d2ea7da0ab2","On the role of multiples in Marchenko imaging","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics)","","2017","","","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:a6b425da-d877-43c1-ac28-8c1b3cd54f09","http://resolver.tudelft.nl/uuid:a6b425da-d877-43c1-ac28-8c1b3cd54f09","Accounting for free-surface multiples in Marchenko imaging","Singh, S.; Snieder, R; van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","Imagine placing a receiver at any location in the earth and recording the response at that location to sources on the surface. In such a world, we could place receivers around our reservoir to better image the reservoir and understand its properties. Realistically, this is not a feasible approach for understanding the subsurface. We have developed an alternative and realizable approach to obtain the response of a buried virtual receiver for sources at the surface. Our method is capable of retrieving the Green’s function for a virtual point in the subsurface to the acquisition surface. In our case, a physical receiver is not required at the subsurface point; instead, we require the reflection measurements for sources and receivers at the surface of the earth and a macromodel of the velocity (no small-scale details of the model are necessary). We can interpret the retrieved Green’s function as the response to sources at the surface for a virtual receiver in the subsurface. We obtain this Green’s function by solving the Marchenko equation, an integral equation pertinent to inverse scattering problems. Our derivation of the Marchenko equation for the Green’s function retrieval takes into account the free-surface reflections present in the reflection response (previous work considered a response without free-surface multiples). We decompose the Marchenko equation into up- and downgoing fields and solve for these fields iteratively. The retrieved Green’s function not only includes primaries and internal multiples as do previous methods, but it also includes freesurface multiples. We use these up- and downgoing fields to obtain a 2D image of our area of interest, in this case, below a synclinal structure.","","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:c3eb7eb2-27cf-43ae-8d99-0ae92fd057b0","http://resolver.tudelft.nl/uuid:c3eb7eb2-27cf-43ae-8d99-0ae92fd057b0","Why multiples do not contribute to deconvolution imaging","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics)","","2017","The question whether multiples are signal or noise is subject of ongoing debate. In this paper we consider correlation and deconvolution imaging methods and analyse to what extent multiples contribute to the image in these methods. Our starting point is the assumption that at a specific depth level the full downgoing and upgoing fields (both including all multiples) are available. First we show that by cross correlating the full downgoing and upgoing wave fields, primaries and multiples contribute to the image. This image is not true-amplitude and is contaminated by cross-talk artefacts. Next we show that by deconvolving the full upgoing field by the full downgoing field, multiples do not contribute to the image. We use minimum-phase arguments to explain this somewhat counterintuitive conclusion. The deconvolution image is true-amplitude and not contaminated by cross-talk artefacts. The conclusion that multiples do not contribute to the image applies to the type of deconvolution imaging analysed in this paper, but should not be extrapolated to other imaging methods. On the contrary, much research is dedicated to using multiples for imaging, for example in full wavefield migration, resonant migration and Marchenko imaging.","","en","conference paper","EAGE","","","","","","","2017-12-31","","","Applied Geophysics and Petrophysics","","","" "uuid:b1b4381d-7219-40b9-84e7-6d7fb8a6120a","http://resolver.tudelft.nl/uuid:b1b4381d-7219-40b9-84e7-6d7fb8a6120a","Sparse Inversion for Solving the Coupled Marchenko Equations Including Free-surface Multiples","Staring, M. (TU Delft Applied Geophysics and Petrophysics); Grobbe, N. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","We compare the coupled Marchenko equations without free-surface multiples to the coupled Marchenko equations including free-surface multiples. When using the conventional method of iterative substitution to solve these equations, a difference in convergence behaviour is observed, suggesting that there is a fundamental difference in the underlying dynamics. Both an intuitive explanation, based on an interferometric interpretation, as well as a mathematical explanation, confirm this difference, and suggest that iterative substitution might not be the most suitable method for solving the system of equations including free-surface multiples. Therefore, an alternative method is required. We propose a sparse inversion, aimed at solving an under-determined system of equations. Results show that the sparse inversion is indeed capable of correctly solving the coupled Marchenko equations including free-surface multiples, even when the iterative scheme fails. Using sparsity promotion and additional constraints, it is expected to perform better than iterative substitution when working with incomplete data or in the presence of noise. Also, simultaneous estimation of the source wavelet is a potential possibility.","","en","conference paper","EAGE","","","","","","","2017-12-31","","","Applied Geophysics and Petrophysics","","","" "uuid:81609a44-8217-47db-b672-2302af612d40","http://resolver.tudelft.nl/uuid:81609a44-8217-47db-b672-2302af612d40","Adaptive double-focusing method for source-receiver Marchenko redatuming on field data","Staring, M. (TU Delft Applied Geophysics and Petrophysics); Pereira, R (CGG); Douma, H; van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","Mihai Popovici, A. (editor); Fomel, S. (editor)","2017","We present an adaptive double-focusing method for applying source-receiver Marchenko redatuming to field data. Receiver redatuming is achieved by a first focusing step, where the coupled Marchenko equations are iteratively solved for the oneway Green’s functions. Next, source redatuming is typically performed by a multi-dimensional deconvolution of these Green’s functions. Instead, we propose a second focusing step for source Marchenko redatuming, using the upgoing Green’s function and the downgoing focusing function to obtain a redatumed reflection response in the physical medium. This method makes adaptive processing more straight-forward, making it less sensitive to imperfections in the data and the acquisition geometry and more suitable for the application to field data. In addition, it is cheaper and can be parallelized by pair of focal points.","","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:95b79ea8-bb03-41d3-8dea-96bdabc8bd41","http://resolver.tudelft.nl/uuid:95b79ea8-bb03-41d3-8dea-96bdabc8bd41","Deconvolution and correlation-based interferometric redatuming by wavefield inversion","Barrera Pacheco, D.F.; Schleicher, J.; van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","Mihai Popovici, A. (editor); Fomel, S. (editor)","2017","Seismic interferometry is a method to retrieve Green’s functions for sources (or receivers) where there are only receivers (or sources, respectively). This can be done by correlationor deconvolution-based methods. In this work we present a

new approach to reposition the seismic array from the earth’s surface to an arbitrary datum at depth using the one-way reciprocity theorems of convolution and correlation type. The redatuming process is done in three steps: (a) retrieving the downward Green’s function for sources at the earth’s surface

and receivers at the datum, (b) retrieving the corresponding upward Green’s function, and (c) retrieving the reflected upward wavefield for sources and receivers at the datum. Input for steps (a) and (b) are the surface data and wavefields simulated in a velocity model of the datum overburden. Step (c)

uses the responses of steps (a) and (b) as input data in the convolution-based interferometric equation. The method accounts for inhomogeneities in the overburden medium, thus reducing anticausal events and artefacts as compared to a purely correlation-based procedure.","","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:6990bd1b-f669-4dc0-ae21-5cf98c0261f4","http://resolver.tudelft.nl/uuid:6990bd1b-f669-4dc0-ae21-5cf98c0261f4","Decomposition of the Green's function using the Marchenko equation","Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","Mihai Popovici, A. (editor); Fomel, S. (editor)","2017","The Marchenko equation can be used to retrieve the Green’s function at depth as a full function or decomposed into its upand downgoing parts. We show that the equation can be rewritten to create a decomposition scheme that can decompose a full wavefield, that was recorded at depth, into its up- and downgoing parts. We show that this can be done without a smooth velocity model that the Marchenko scheme requires and without any knowledge of the medium properties that traditional decomposition methods require. Instead we only need a the reflection response and a wavefield that has been recorded at the

surface due to a source at depth or (by using source-receiver reciprocity) that was measured down in a borehole due to a source at the surface. We also validate our results by comparing them to directly modeled up- and downgoing wavefields.","","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:2cc566bf-9d49-43b6-8abb-bdb6e2d4bcbd","http://resolver.tudelft.nl/uuid:2cc566bf-9d49-43b6-8abb-bdb6e2d4bcbd","Applying source-receiver Marchenko redatuming to field data, using an adaptive double-focusing method","Staring, M. (TU Delft Applied Geophysics and Petrophysics); Pereira, Roberto (CGG, Rio de Janeiro); Douma, Huub; van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2017","In this paper, we focus on the field data application of source-receiver Marchenko redatuming. Conventionally, a source-receiver redatumed reflection response is obtained by first applying the Marchenko method for receiver-redatuming and then performing a multi-dimensional deconvolution (MDD) for sourceredatuming (Wapenaar et al. (2014)). The obtained reflection response is free from any interactions with the overburden. However, the MDD solves an ill-posed inverse problem (van der Neut et al. (2011a)), which makes it sensitive to imperfections in the data and the acquisition geometry. This is a problem for the field data application, since neither the data nor the acquisition geometry are ever perfect. In addition, MDD is computationally expensive.","","en","conference paper","","","","","","","","","","","","","","" "uuid:9289514b-58c6-4e80-948b-fed8dcafa4e1","http://resolver.tudelft.nl/uuid:9289514b-58c6-4e80-948b-fed8dcafa4e1","Unified double- and single-sided homogeneous Green's function representations","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics)","","2016","In wave theory, the homogeneous Green’s function consists of the impulse response to a point source, minus its time-reversal. It can be represented by a closed boundary integral. In many practical situations, the closed boundary integral needs to be approximated by an open boundary integral because the medium of interest is often accessible from one side only. The inherent approximations are acceptable as long as the effects of multiple scattering are negligible. However, in case of strongly inhomogeneous media, the effects of multiple scattering can be severe. We derive double- and single-sided homogeneous Green’s function representations. The single-sided representation applies to situations where the medium can be accessed from one side only. It correctly handles multiple scattering. It employs a focusing function instead of the backward propagating Green’s function in the classical (double-sided) representation. When reflection measurements are available at the accessible boundary of the medium, the focusing function can be retrieved from these measurements. Throughout the paper, we use a unified notation which applies to acoustic, quantum-mechanical, electromagnetic and elastodynamic waves. We foresee many interesting applications of the unified single-sided homogeneous Green’s function representation in holographic imaging and inverse scattering, time-reversed wave field propagation and interferometric Green’s function retrieval.","","en","journal article","","","","","","","","2017-07-31","","","Applied Geophysics and Petrophysics","","","" "uuid:0d0cf38b-e8ea-4b7a-9e8f-b0a0e81e97a1","http://resolver.tudelft.nl/uuid:0d0cf38b-e8ea-4b7a-9e8f-b0a0e81e97a1","Adaptive overburden elimination with the multidimensional Marchenko equation","van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2016","Imagine placing a receiver at any location in the earth and recording the response at that location to sources on the surface. In such a world, we could place receivers around our reservoir to better image the reservoir and understand its properties. Realistically, this is not a feasible approach for understanding the subsurface. We have developed an alternative and realizable approach to obtain the response of a buried virtual receiver for sources at the surface. Our method is capable of retrieving the Green’s function for a virtual point in the subsurface to the acquisition surface. In our case, a physical receiver is not required at the subsurface point; instead, we require the reflection measurements for sources and receivers at the surface of the earth and a macromodel of the velocity (no small-scale details of the model are necessary). We can interpret the retrieved Green’s function as the response to sources at the surface for a virtual receiver in the subsurface. We obtain this Green’s function by solving the Marchenko equation, an integral equation pertinent to inverse scattering problems. Our derivation of the Marchenko equation for the Green’s function retrieval takes into account the free-surface reflections present in the reflection response (previous work considered a response without free-surface multiples). We decompose the Marchenko equation into up- and downgoing fields and solve for these fields iteratively. The retrieved Green’s function not only includes primaries and internal multiples as do previous methods, but it also includes freesurface multiples. We use these up- and downgoing fields to obtain a 2D image of our area of interest, in this case, below a synclinal structure.","","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:aeefaee3-3d1f-48f8-b9a2-131971ca5e55","http://resolver.tudelft.nl/uuid:aeefaee3-3d1f-48f8-b9a2-131971ca5e55","Combination of surface and borehole seismic data for robust target-oriented imaging","Liu, Yi (Norwegian University of Science and Technology); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Arntsen, B; Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2016","A novel application of seismic interferometry (SI) and Marchenko imaging using both surface and borehole data is presented. A series of redatuming schemes is proposed to combine both data sets for robust deep local imaging in the presence of velocity uncertainties. The redatuming schemes create a virtual acquisition geometry where both sources and receivers lie at the horizontal borehole level, thus only a local velocity model near the borehole is needed for imaging, and erroneous velocities in the shallow area have no effect on imaging around the borehole level. By joining the advantages of SI and Marchenko imaging, a macrovelocity model is no longer required and the proposed schemes use only single-component data. Furthermore, the schemes result in a set of virtual data that have fewer spurious events and internal multiples than previous virtual source redatuming methods. Two numerical examples are shown to illustrate the workflow and to demonstrate the benefits of the method. One is a synthetic model and the other is a realistic model of a field in the North Sea. In both tests, improved local images near the boreholes are obtained using the redatumed data without accurate velocities, because the redatumed data are close to the target.","Inverse theory; Downhole methods; Interferometry; Wave propagation","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:3b45c9ec-e3da-4997-8f92-e89271b442c9","http://resolver.tudelft.nl/uuid:3b45c9ec-e3da-4997-8f92-e89271b442c9","A single-sided homogeneous Green's function representation for holographic imaging, inverse scattering, time-reversal acoustics and interferometric Green's function retrieval","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics)","","2016","Green's theorem plays a fundamental role in a diverse range of wavefield imaging applications, such as holographic imaging, inverse scattering, time-reversal acoustics and interferometric Green's function retrieval. In many of those applications, the homogeneous Green's function (i.e. the Green's function of the wave equation without a singularity on the right-hand side) is represented by a closed boundary integral. In practical applications, sources and/or receivers are usually present only on an open surface, which implies that a significant part of the closed boundary integral is by necessity ignored. Here we derive a homogeneous Green's function representation for the common situation that sources and/or receivers are present on an open surface only. We modify the integrand in such a way that it vanishes on the part of the boundary where no sources and receivers are present. As a consequence, the remaining integral along the open surface is an accurate single-sided representation of the homogeneous Green's function. This single-sided representation accounts for all orders of multiple scattering. The new representation significantly improves the aforementioned wavefield imaging applications, particularly in situations where the first-order scattering approximation breaks down.","Controlled source seismology; Interferometry; Wave scattering and diffraction","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:e5a47613-6f6c-48a6-a81e-16430c319586","http://resolver.tudelft.nl/uuid:e5a47613-6f6c-48a6-a81e-16430c319586","Electromagnetic Marchenko imaging in 1D for dissipative media","Zhang, L. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Staring, M. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","Sicking, Charles (editor); Ferguson, John (editor)","2016","We present a one-dimensional lossless scheme to compute an image of a dissipative medium from two single-sided reflection responses. One reflection response is measured at or above the top reflector of a dissipative medium and the other reflection response is computed as if measured at or above the top reflector of a medium with negative dissipation which we call the effectual medium. These two reflection responses together can be used to construct the approximate reflection data of the corresponding lossless medium by multiplying and taking the square root in time domain. The corresponding lossless medium has the same reflectors as the dissipative medium. Then the constructed reflection data can be used to compute the focusing wavefield which focuses at the chosen location in subsurface of the dissipative medium. From the focusing function and constructed reflection response the Green’s function for a virtual receiver can be obtained. Because the up- and downgoing parts of the Green’s function are retrieved separately, these are used to compute the image. We show with an example that the method works well for a sample in a synthesized waveguide that could be used for measurements in a laboratory.","electromagnetic; conductivity; internal multiples; permeability; GPR","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:55668444-8773-44ce-a542-b28883d3654c","http://resolver.tudelft.nl/uuid:55668444-8773-44ce-a542-b28883d3654c","Marchenko wavefield redatuming, imaging conditions, and the effect of model errors","de Ridder, Sjoerd (University of Edinburgh); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Curtis, A (University of Edinburgh); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","Sicking, Charles (editor); Ferguson, John (editor)","2016","Recently, a novel method to redatum the wavefield in the sub-surface from a reflection response measured at the surface has gained interest for imaging primaries in the presence of strong internal multiples. A prerequisite for the algorithm is an accurate and correct estimate of the direct-wave Green's function. However, usually we use an estimate for the direct-wave Green's function computed in a background velocity medium. Here, we investigate the effect of amplitude and phase errors in that estimate. We formulate two novel imaging conditions based on double-focusing the measured reflection response inside the subsurface. These yield information on the amplitude error in the estimate for the direct-wave Green's function which we can then correct, but the phase error remains elusive.","inversion; autofocusing; imaging; internal multiples; velocity","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:170cc1de-39a6-4906-ad7a-935382da4232","http://resolver.tudelft.nl/uuid:170cc1de-39a6-4906-ad7a-935382da4232","New method for discriminating 4D time shifts in the overburden and reservoirr","Liu, Yi (Norwegian University of Science and Technology); Arntsen, B (Norwegian University of Science and Technology); Landrö, M (Norwegian University of Science and Technology); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","Sicking, Charles (editor); Ferguson, John (editor)","2016","Understanding seismic changes in the subsurface is important for reservoir management and health, safety and environmental (HSE) issues. Typically the changes are interpreted based on the time shifts in seismic time-lapse (4D) data, where sources are at the surface and receivers are either at the surface or in a borehole. With these types of acquisition geometry, it is more straightforward to detect and interpret changes in the overburden, close to the source and receivers, than changes in the deeper part close to the reservoir, because the time shift is accumulative along its ray path from source to receiver. We propose a new method for reconstructing the reflection responses of the overburden and the reservoir, separately, for 4D time shift analysis. This method virtually moves sources and receivers to a horizontal borehole level, which enables a more direct interpretation of the time shifts to the changes close to the borehole, instead of to the surface. A realistic field model is used to demonstrate the method, and we observe a clear discrimination of the different time shifts in the overburden and reservoir, which is not obvious in the original datasets.","reconstruction; time-lapse; traveltime; downhole receivers; internal multiples","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:0527c923-f2f4-422f-928c-c8fd3d9e6295","http://resolver.tudelft.nl/uuid:0527c923-f2f4-422f-928c-c8fd3d9e6295","Beyond Marchenko: Obtaining virtual receivers and virtual sources in the subsurface","Singh, S. (Colorado School of Mines); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Snieder, R (Colorado School of Mines)","Sicking, Charles (editor); Ferguson, John (editor)","2016","By solving the Marchenko equations, the Green’s function can be retrieved between a virtual receiver in the subsurface to points at the surface (no physical receiver is required at the virtual location). We extend the idea of these equations to retrieve the Green’s function between any two points in the subsurface; i.e, between a virtual source and a virtual receiver (no physical source or physical receiver is required at either of these locations). This Green’s function is called the virtual Green’s function and includes all the primaries, internal and free-surface multiples. Similar to the Marchenko Green’s function, we require the reflection response at the surface (single-sided illumination) and an estimate of the first arrival travel time from the virtual location to the surface.","multiples; scattering; downhole sources; downhole receivers; autofocusing","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:37a5a787-e388-49f5-9c22-579dee5aa1ef","http://resolver.tudelft.nl/uuid:37a5a787-e388-49f5-9c22-579dee5aa1ef","From closed-boundary to single-sided homogeneous Green's function representations","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Singh, Satyan (University of the West Indies)","Sicking, Charles (editor); Ferguson, John (editor)","2016","The homogeneous Green’s function (i.e., the Green’s function and its time-reversed counterpart) plays an important role in optical, acoustic and seismic holography, in inverse scattering methods, in the field of time-reversal acoustics, in reversetime migration and in seismic interferometry. Starting with the classical closed-boundary representation of the homogeneous Green’s function, we modify the configuration to two parallel boundaries. We discuss step-by-step a process that eliminates the integral along the lower boundary. This leads to a single-sided representation of the homogeneous Green’s function. Apart from imaging, we foresee interesting applications in inverse scattering, time-reversal acoustics, seismic interferometry, passive source imaging, etc.","imaging; internal multiples","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:752f1f22-26f5-42e0-9d5e-70aaf95042aa","http://resolver.tudelft.nl/uuid:752f1f22-26f5-42e0-9d5e-70aaf95042aa","An interferometric interpretation of Marchenko redatuming including free-surface multiples","Staring, M. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","Sicking, Charles (editor); Ferguson, John (editor)","2016","We present an interferometric interpretation of the iterative Marchenko scheme including both free-surface multiples and internal multiples. Cross-correlations are used to illustrate the combination of causal and acausal events that are essential for the process of multiple removal. The first 4 steps in the scheme are discussed in detail, where the effect of different contributions on the result is displayed and the formation of individual events is illustrated. We highlight the events that are necessary to understand the process that removes both internal multiples and free-surface multiples from the data. We demonstrate that additional contributions are needed to correct for the presence of free-surface multiples.","multiples; seismic; autofocusing; correlation","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:28ababd6-a8bb-46b8-8145-699d1b07106b","http://resolver.tudelft.nl/uuid:28ababd6-a8bb-46b8-8145-699d1b07106b","Imaging the earth's interior with virtual sources and receivers","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Snieder, R (Extern)","","2016","","","en","abstract","","","","","","","","","","","","","","" "uuid:ef15255e-c92c-4615-bd63-b9525f7e25db","http://resolver.tudelft.nl/uuid:ef15255e-c92c-4615-bd63-b9525f7e25db","Marchenko imaging: Imaging with primaries, internal multiples, and free-surface multiples","Singh, S.; Snieder, R.; Behura, J.; van der Neut, J.R.; Wapenaar, C.P.A.; Slob, E.C.","","2015","Recent work on retrieving the Green’s function with the Marchenko equation shows how these functions for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green’s function from the location of the virtual source to the surface. The Green’s function is retrieved using only the reflection response of the medium and an estimate of the first arrival at the surface from the virtual source. Current techniques, however, only include primaries and internal multiples. Therefore, all surface-related multiples must be removed from the reflection response prior to Green’s function retrieval. We have extended the Marchenko equation to retrieve the Green’s function that includes primaries, internal multiples, and free-surface multiples. In other words, we have retrieved the Green’s function in the presence of a free surface. The information needed for the retrieval is the same as the current techniques, with the only difference being that the reflection response now also includes free-surface multiples. The inclusion of these multiples makes it possible to include them in the imaging operator, and it obviates the need for surface-related multiple elimination. This type of imaging with Green’s functions is called Marchenko imaging.","multiples; scattering; imaging; reflectivity; reciprocity","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","","" "uuid:a3762abc-0fae-4b0b-bea6-aa571f2db3e2","http://resolver.tudelft.nl/uuid:a3762abc-0fae-4b0b-bea6-aa571f2db3e2","Autofocusing imaging: Imaging with primaries, internal multiples and free-surface multiples","Singh, S.; Snieder, R.; Behura, J.; van der Neut, J.R.; Wapenaar, C.P.A.; Slob, E.C.","","2014","Recent work on autofocusing with the Marchenko equation has shown how the Green's function for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green's function from the location of the virtual source to the surface. The Green's function is retrieved using only the reflection response of the medium and an estimate of the first arrival at the surface from the virtual source. Current techniques, however, only include primaries and internal multiples. Therefore, all surface-related multiples must be removed from the reflection response prior to Green's function retrieval. Here, we extend the Marchenko equation to retrieve the Green's function that includes primaries, internal multiples, and free-surface multiples. In other words, we retrieve the Green's function in the presence of a free surface. We use the associated Green's function for imaging the subsurface. The information needed for the retrieval are the reflection response at the surface and an estimate of the first arrival at the surface from the virtual source. The reflection response, in this case, includes the free-surface multiples; this makes it possible to include these multiples in the imaging operator and it obviates the need for surface-related multiple elimination.","imaging; multiples; scattering; autofocusing; internal multiples","en","conference paper","SEG","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","","" "uuid:640f712d-dd99-4a5c-a65f-6e2fdcc50ba9","http://resolver.tudelft.nl/uuid:640f712d-dd99-4a5c-a65f-6e2fdcc50ba9","Wavefield decomposition of field data, using a shallow horizontal downhole sensor array and a free-surface constraint","Grobbe, N.; van der Neut, J.R.; Almagro Vidal, C.; Drijkoningen, G.G.; Wapenaar, C.P.A.","","2014","Separation of recorded wavefields into downgoing and upgoing constituents is a technique that is used in many geophysical methods. The conventional, multi-component (MC) wavefield decomposition scheme makes use of different recorded wavefield components. In recent years, land acquisition designs have emerged that make use of shallow horizontal downhole sensor arrays. Inspired by marine acquisitiondesigns that make use of recordings at multiple depth levels for wavefield decomposition, we have recently developed a multi-depth level (MDL) wavefield decomposition scheme for land acquisition. Exploiting the underlying theory of this scheme, we now consider conventional, multi-component (MC) decomposition as an inverse problem, which we try to constrain in a better way. We have overdetermined the inverse problem by adding an MDL equation that exploits the Dirichlet free-surface boundary condition. To investigate the successfulness of this approach, we have applied both MC and combined MC-MDL decomposition to a real land dataset acquired in Annerveen, the Netherlands. Comparison of the results of overdetermined MC-MDL decomposition with the results of MC wavefield decomposition, clearly shows improvements in the obtained one-way wavefields, especially for the downgoing fields.","","en","conference paper","EAGE","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""