Searched for: collection%3Air
(1 - 20 of 168)

Pages

document
Wapenaar, C.P.A. (author), Brackenhoff, J.A. (author), Thorbecke, J.W. (author), van der Neut, J.R. (author), Slob, E.C. (author), Verschuur, D.J. (author)
A virtual acoustic source inside a medium can be created by emitting a time-reversed point-source response from the enclosing boundary into the medium. However, in many practical situations the medium can be accessed from one side only. In those cases the time-reversal approach is not exact. Here, we demonstrate the experimental design and...
journal article 2018
document
Meles, G.A. (author), Wapenaar, C.P.A. (author), Thorbecke, J.W. (author)
Marchenko redatuming is a novel scheme used to retrieve up- and downgoing Green's functions in an unknown medium.Marchenko equations are based on reciprocity theorems and are derived on the assumption of the existence of functions exhibiting space-time focusing properties once injected in the subsurface. In contrast to interferometry but...
journal article 2018
document
Wapenaar, C.P.A. (author), Staring, M. (author)
In seismic monitoring, one is usually interested in the response of a changing target zone, embedded in a static inhomogeneous medium. We introduce an efficient method that predicts reflection responses at the Earth's surface for different target-zone scenarios, from a single reflection response at the surface and a model of the changing...
journal article 2018
document
Harmankaya, U (author), Kaslilar, A. (author), Wapenaar, C.P.A. (author), Draganov, D.S. (author)
Unexpected geological structures can cause safety and economic risks during underground excavation. Therefore, predicting possible geological threats while drilling a tunnel is important for operational safety and for preventing expensive standstills. Subsurface information for tunneling is provided by exploratory wells and by surface...
journal article 2018
document
Hartstra, I.E. (author), Almagro Vidal, C. (author), Wapenaar, C.P.A. (author)
Virtual Green's functions obtained by seismic interferometry (SI) can provide valuable reflectivity data that can complement tomographic inversion schemes. However, virtual reflections are affected by illumination irregularities that are typical of earthquake-induced wavefields recorded by the receiver array. As a consequence, irregular...
journal article 2018
document
Cui, Tianci (author), Vasconcelos, Ivan (author), Manen, Dirk Jan Van (author), Wapenaar, C.P.A. (author)
Marchenko redatuming can retrieve the impulse response to a subsurface virtual source from the single-sided surface reflection data with limited knowledge of the medium. We illustrate the concepts and practical aspects of Marchenko redatuming on a simple 1D acoustic lossless medium in which the coupled Marchenko equations are exact. Defined...
journal article 2018
document
Almagro Vidal, C. (author), van der Neut, J.R. (author), Verdel, Arie (author), Hartstra, I.E. (author), Wapenaar, C.P.A. (author)
Passive seismic interferometry enables the estimation of the reflection response of the subsurface using passive receiver recordings at the surface from sources located deep in the Earth. Interferometric imaging makes use of this retrieved reflection response in order to study the subsurface. Successful interferometric imaging relies on the...
journal article 2018
document
Zhang, L. (author), Slob, E.C. (author), van der Neut, J.R. (author), Wapenaar, C.P.A. (author)
We have derived an improved reverse time migration (RTM) scheme to image the medium without artifacts arising from internal multiple reflections. This is based on a revised implementation of Marchenko redatuming using a new time-truncation operator. Because of the new truncation operator, we can use the time-reversed version of the standard...
journal article 2018
document
Thorbecke, J.W. (author), Slob, E.C. (author), Brackenhoff, J.A. (author), van der Neut, J.R. (author), Wapenaar, C.P.A. (author)
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...
journal article 2017
document
Liu, Y. (author), Landrø, Martin (author), Arntsen, Børge (author), van der Neut, J.R. (author), Wapenaar, C.P.A. (author)
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...
journal article 2017
document
Slob, E.C. (author), Wapenaar, C.P.A. (author)
We present a three-dimensional scheme that can be used to compute the electromagnetic impulse response between any two subsurface points from surface reflection data measured at a single surface of a lossless medium. The scheme first computes a virtual vertical radar profile using the Marchenko scheme from which focusing wavefields are...
conference paper 2017
document
van der Neut, J.R. (author), Johnson, Jami L. (author), van Wijk, K. (author), Singh, S. (author), Slob, E.C. (author), Wapenaar, C.P.A. (author)
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...
journal article 2017
document
Wapenaar, C.P.A. (author)
journal article 2017
document
Ruigrok, E.N. (author), Gibbons, Steven (author), Wapenaar, C.P.A. (author)
An areal distribution of sensors can be used for estimating the direction of incoming waves through beamforming. Beamforming may be implemented as a phase-shifting and stacking of data recorded on the different sensors (i.e., conventional beamforming). Alternatively, beamforming can be applied to cross-correlations between the waveforms on...
journal article 2017
document
Weemstra, C. (author), Draganov, D.S. (author), Ruigrok, E.N. (author), Hunziker, J.W. (author), Gomez, Martin (author), Wapenaar, C.P.A. (author)
Obtaining new seismic responses from existing recordings is generally referred to as seismic interferometry (SI). Conventionally, the SI responses are retrieved by simple crosscorrelation of recordings made by separate receivers: one of the receivers acts as a ‘virtual source’ whose response is retrieved at the other receivers.When SI is applied...
journal article 2017
document
Weemstra, C. (author), Wapenaar, C.P.A. (author), van Dalen, K.N. (author)
Seismic interferometry (SI) takes advantage of existing (ambient) wavefield recordings by turning receivers into so-called “virtual-sources.” The medium’s response to these virtual sources can be harnessed to image that medium. Applications of SI include surface-wave imaging of the Earth’s shallow subsurface and medical imaging. Most...
journal article 2017
document
Evers, L.G. (author), Wapenaar, C.P.A. (author), Heaney, KD (author), Snellen, M. (author)
The propagation of acoustic waves in the ocean strongly depends on the temperature. Lowfrequency acoustic waves can penetrate the ocean down to depths where few in situ measurements are available. It is therefore attractive to obtain a measure of the deep ocean temperature from acoustic waves. The latter is especially true if the ambient...
journal article 2017
document
Wapenaar, C.P.A. (author), van der Neut, J.R. (author), Slob, E.C. (author)
journal article 2017
document
Singh, S. (author), Snieder, R (author), van der Neut, J.R. (author), Thorbecke, J.W. (author), Slob, E.C. (author), Wapenaar, C.P.A. (author)
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...
journal article 2017
document
Holicki, M.E. (author), Drijkoningen, G.G. (author), Wapenaar, C.P.A. (author)
We propose a novel directional decomposition operator for wavefield snapshots in heterogeneous-velocity media. The proposed operator demonstrates the link between the amplitude of pressure and particlevelocity plane waves in the wavenumber domain. The proposed operator requires two spatial Fourier transforms (one forward and one backward) per...
conference paper 2017
Searched for: collection%3Air
(1 - 20 of 168)

Pages