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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
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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
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Li, Y. (author), Lu, H. (author), Wang, L. (author), Eltayieb, M.F.M.I. (author), Slob, E.C. (author)
Natural gas hydrates production tests over the last two decades has sown that production is not without risks. Indirect effects in the sedimentary rocks of phase changes are changes in porosity, permeability, and saturation. From a field production test site, porosity changes in the range of 15% to 19% and saturation from 5% to 60% were...
conference paper 2022
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Karimpour, M. (author), Slob, E.C. (author), Socco, L. V. (author)
Surface Wave Tomography (SWT) is used to build shear-wave velocity models. In some studies, it is assumed that surface waves propagation follows a straight line between the source and the receiver. This assumption might be violated in near-surface studies because of high level of complexity and lateral heterogeneity. In curved-ray SWT, the...
conference paper 2022
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Calderon Hernandez, O.I. (author), Slob, E.C. (author), Socco, Laura Valentina (author)
Over the last years, new techniques are being researched in order directly estimate relevant geological properties of the rocks present in the subsurface without using an inversion process, this can be achieved by obtaining relationships between the data obtained by geophysical surveys and the data obtained in one place by well logging, core...
conference paper 2022
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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
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Slob, E.C. (author), Draganov, D.S. (author), Eltayieb, M.F.M.I. (author), Drijkoningen, G.G. (author), Werthmüller, D. (author), Ghose, R. (author)
Difficulties in detecting and characterising shallow objects close the surface with seismic shear waves are often problematic because of dominant surface waves. By sequencing a specific combination of two data driven processing steps followed by diffraction tomography can overcome these problems. Small scattering objects become visible in the...
conference paper 2021
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Slob, E.C. (author), Zhang, L. (author)
The ability to separate primary reflections from multiples is important for making subsurface images. Many existing methods need some form of model information and adaptive subtraction. Marchenko methods have been modified to operate at the acquisition surface. The associated filters can be computed from the reflection response without any model...
conference paper 2020
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Abolhassani, S. (author), Slob, E.C. (author), Vossepoel, F.C. (author)
Considering the steadily declining prices in the oil and gas industry, nowadays, the requirement for geophysical information becomes more important in order to get the most out of available reservoirs. Electromagnetic measurements could complement seismic data where it lacks information. The EM response to fluid fill complements the resolving...
conference paper 2020
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Werthmüller, D. (author), Slob, E.C. (author)
Modelling time-domain electromagnetic data with a frequency-domain code requires the computation of many<br/>frequencies for the Fourier transform. This can make it computationally very expensive when compared with timedomain codes. However, it has been shown that frequency-domain codes can be competitive if frequencydependent modelling grids...
conference paper 2020
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Karimpour, M. (author), Slob, E.C. (author), Socco, LV (author)
Surface Wave Tomography is used to obtain a shear wave velocity model by inverting computed dispersion curves. Body Wave Tomography is used to obtain a longitudinal wave model through travel time inversion of picked first break travel times. Individual inversions suffer from various different limitations. Joint surface and body wave tomography...
conference paper 2020
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Slob, E.C. (author), Zhang, L. (author)
Marchenko methods compute a focusing function for a receiver at the acquisition surface and a virtual source in the subsurface. Computing the focusing function requires subsurface information. The method has been modified to operate at the acquisition surface. The focusing function becomes a fundamental wave field as known since many decades....
conference paper 2020
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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
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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
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Zhou, F. (author), Giannakis, Iraklis (author), Giannopoulos, Antonios (author), Slob, E.C. (author)
In the phase of oil drilling, mud filtrate penetrates into porous formations and alters the pore fluid properties. This complicates well logging exploration, and inevitably gives rise to shift in reservoir estimation. Logging engineers deem mud invasion a harm and attempt to eliminate its impact on logging data exploration. However, from our...
conference paper 2019
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Slob, E.C. (author), Zhang, L. (author)
Elimination of multiples from acoustic reflection data is important to reduce the effect of their presence in velocity model building and subsequent imaging. Many processing schemes assume only primary reflection events are present in the data. Free-surface multiple elimination is an established technology, but internal multiple elimination is...
conference paper 2019
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Zhang, L. (author), Slob, E.C. (author)
We compare two data-driven internal multiple reflection elimination schemes derived from regular Marchenko equations and Inverse Scattering Series (ISS). The scheme derived from regular Marchenko equations creates a new data set without internal multiple reflections. The scheme derived from ISS is equal to the result after the second...
conference paper 2019
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Slob, E.C. (author)
For a long time free surface related multiple reflection were removed before further processing was done. Based on the recently developed Marchenko type redatuming theory a theory was developed that is able to remove surface related and internal multiples during the redatuming step. This requires some model information that is avoided by...
conference paper 2019
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Zhang, L. (author), Slob, E.C. (author)
Multiple reflections are often considered as noise in seismic data. Dealing with them has attracted much attention from industry and academia. A variety of schemes have been developed for removal of free-surface multiple reflections and success has been achieved in numerical and field datasets. However, less attention has been directed toward...
conference paper 2019
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Yang, B. (author), Slob, E.C. (author)
We present a data driven method of full waveform inversion in one dimension. This means that the inversion is carried out as a sequence of processing steps. The first step is known as Marchenko redatuming. In this step we retrieve focusing functions from the measured data. In the second step we isolate the last event in the focusing function to...
conference paper 2018
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