by separate receivers: a first receiver acts as a 'virtual source' whose response is retrieved at the other receivers. When surface waves are retrieved, the newly retrieved responses can be used to extract receiver-receiver phase velocities. These phase velocities often serve as input parameters for tomographic inverse problems. Another application of SI exploits the temporal stability of the multiply scattered arrivals (the coda). For all applications, however, the accuracy of the retrieved responses is paramount. In practice, this accuracy is often degraded by irregularities in the illumination pattern: correct response retrieval relies on a uniform illumination of the receivers. Reformulating the theory underlying seismic interferometry by crosscorrelation as a multidimensional deconvolution (MDD) process, allows for correction of these non-uniform illumination patterns by means of a so-called point-spread function (PSF). We apply SI by MDD to surface-wave data recorded by the Malargüe seismic array in western Argentina. The aperture of the array is approximately 60 km and it is located on a plateau just east of the Andean mountain range. The array has a T-shape, which makes it very well suited for the application of SI by MDD. We select time windows dominated by surface-wave noise traveling in a favorable direction, that is, traversing the line of virtual sources before arriving at the receivers at which we aim to retrieve the virtual-source responses. These time windows are selected based upon the slownesses along the two receiver lines. From the selected time windows, virtual-source responses are retrieved by computation of ensemble-averaged crosscorrelations. Similarly, ensemble-averaged crosscorrelations between the positions of the virtual sources are computed: the PSF. We use the PSF to deconvolve the effect of illumination irregularities and the source function from the virtual-source responses retrieved by crosscorrelation. The combined effect of time-window selection and MDD results in more accurate and temporally stable surface-wave responses.","","en","abstract","","","","","","","Campus only","","","","","","","" "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: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: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: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:a6cb1a31-23c9-46f0-9a52-b1f68378d57f","http://resolver.tudelft.nl/uuid:a6cb1a31-23c9-46f0-9a52-b1f68378d57f","Time-slice wavefield decomposition","Holicki, M.E. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Drijkoningen, G.G. (TU Delft Applied Geophysics and Petrophysics)","Sicking, Charles (editor); Ferguson, John (editor)","2016","We propose a novel acoustic decomposition operator for time slices, loosely based on conventional surface decomposition operators. The proposed operators hold for constant velocity models and require two 2D Fourier Transforms (one forward, one backward) per decomposed time slice per decomposition direction. We then demonstrate the capabilities of our operators on a constant velocity model and the Marmousi model. The decomposition results prove that we can decompose into up-, down-, left- and right-going waves for complex velocity media.","imaging; internal multiples","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:8ea16a77-0ce5-4464-af8b-ba4e4a1c309d","http://resolver.tudelft.nl/uuid:8ea16a77-0ce5-4464-af8b-ba4e4a1c309d","Marchenko equations for acoustic Green's function retrieval and imaging in dissipative media","Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (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 scheme for Marchenko imaging in a dissipative heterogeneous medium. The scheme requires measured reflection and transmission data at two sides of the dissipative medium. The effectual medium is the same as the dissipative medium, but with negative dissipation. We show how the measured double-sided data can be combined to obtain the single-sided reflection response of the effectual medium. Two sets of single-sided Marchenko equations follow that are used to compute to the focusing wavefield and the Green functions. Each uses single-sided reflection responses of the dissipative and effectual medium. To start the solution for these equations an initial estimate of the dissipation is required in addition to the estimate of the travel time of the first arrival. Avoiding the estimate of dissipation of the first arrival in a low-loss medium does not have a detrimental effects on the image quality. The numerical example shows the effectiveness of this strategy.","attenuation; autofocusing; multiples; 3D","en","conference paper","SEG","","","","","","","","","","","","","" "uuid:18cd9b28-07ea-4151-9952-81aca9f8d65f","http://resolver.tudelft.nl/uuid:18cd9b28-07ea-4151-9952-81aca9f8d65f","Reflection imaging of the Moon's interior using deep-moonquake seismic interferometry","Nishitsuji, Y. (TU Delft Applied Geophysics and Petrophysics); Rowe, CA (Los Alamos National Laboratory); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Draganov, D.S. (TU Delft Applied Geophysics and Petrophysics)","","2016","The internal structure of the Moon has been investigated over many years using a variety of seismic methods, such as travel time analysis, receiver functions, and tomography. Here we propose to apply body-wave seismic interferometry to deep moonquakes in order to retrieve zero-offset reflection responses (and thus images) beneath the Apollo stations on the nearside of the Moon from virtual sources colocated with the stations. This method is called deep-moonquake seismic interferometry (DMSI). Our results show a laterally coherent acoustic boundary around 50 km depth beneath all four Apollo stations. We interpret this boundary as the lunar seismic Moho. This depth agrees with Japan Aerospace Exploration Agency's (JAXA) SELenological and Engineering Explorer (SELENE) result and previous travel time analysis at the Apollo 12/14 sites. The deeper part of the image we obtain from DMSI shows laterally incoherent structures. Such lateral inhomogeneity we interpret as representing a zone characterized by strong scattering and constant apparent seismic velocity at our resolution scale (0.2–2.0 Hz).","","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:f940c8ab-a08f-4404-b529-4491af1d6887","http://resolver.tudelft.nl/uuid:f940c8ab-a08f-4404-b529-4491af1d6887","Reflection imaging of aseismic zones of the Nazca slab by global-phase seismic interferometry","Nishitsuji, Y. (TU Delft Applied Geophysics and Petrophysics); Ruigrok, E (Utrecht University); Gomez, M (Comision Nacional de Energia Atomica); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Draganov, D.S. (TU Delft Applied Geophysics and Petrophysics)","","2016","Obtaining detailed images of aseismic parts of subducting slabs remains a large challenge for understanding slab dynamics. Hypocenter mapping cannot be used for the purpose due to the absence of seismicity, whereas the use of receiver functions might be compromised by the presence of melt. Global tomography can be used to identify the presence of the slab, but it does not reveal the structure in detail. We have determined how detailed images can be obtained using global-phase seismic interferometry. The method provides high-resolution (<15km in depth) pseudo zero-offset (i.e., colocated source and receiver) reflection information. We have applied the method to aseismic zones of the Nazca slab in which initiation of possible slab tearing and plume decapitation was identified by global tomography and electrical conductivity, respectively. We have obtained an image of the Moho and the mantle and found an attenuated area in the image consistent with the presence of an aseismic dipping subducting slab. However, our interpretation was not unambiguous. The results confirmed that the method is useful for imaging aseismic transects of slabs.","acoustic; earthquake; illumination; interferometry; interpretation","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:d32648a7-16e7-439d-be9f-bd40e3161a7d","http://resolver.tudelft.nl/uuid:d32648a7-16e7-439d-be9f-bd40e3161a7d","Crustal-scale reflection imaging and interpretation by passive seismic interferometry using local earthquakes","Nishitsuji, Y. (TU Delft Applied Geophysics and Petrophysics); Minato, S. (TU Delft Applied Geophysics and Petrophysics); Boullenger, B. (TU Delft Applied Geophysics and Petrophysics); Gomez, M (Comision Nacional de Energia Atomica); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Draganov, D.S. (TU Delft Applied Geophysics and Petrophysics)","","2016","We have developed an application of passive seismic interferometry (SI) using P-wave coda of local earthquakes for the purpose of crustal-scale reflection imaging. We processed the reflection gathers retrieved from SI following a standard seismic processing in exploration seismology. We applied SI to the P-wave coda using crosscorrelation, crosscoherence, and multidimensional deconvolution (MDD) approaches for data recorded in the Malargüe region, Argentina. Comparing the results from the three approaches, we found that MDD based on the truncated singular-value decomposition scheme gave us substantially better structural imaging. Although our results provided higher resolution images of the subsurface, they showed less clear images for the Moho in comparison with previous seismic images in the region obtained by the receiver function and global-phase SI. Above the Moho, we interpreted a deep thrust fault and the possible melting zones, which were previously indicated by active-seismic and magnetotelluric methods in this region, respectively. The method we developed could be an alternative option not only for crustal-scale imaging, e.g., in enhanced geothermal systems, but also for lithospheric-scale as well as basin-scale imaging, depending on the availability of local earthquakes and the frequency bandwidth of their P-wave coda.","acoustic; crustal structure; earthquake; interferometry; geothermal","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:0b3a6327-387d-4d8a-97d3-92d0c0340f9f","http://resolver.tudelft.nl/uuid:0b3a6327-387d-4d8a-97d3-92d0c0340f9f","Homogeneous Green’s function retrieval using the Marchenko method","Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2017","In wave theory, a Green’s function is defined as the response of a medium to an impulsive point source. The homogeneous Green’s function is the combination of the Green’s function and its time-reversal. Homogeneous Green’s functions can be retrieved if the medium is enclosed by a boundary where the full wavefield is recorded. In recent years, the Marchenko method has gained popularity, because unlike many conventional methods it does not require an enclosing boundary. Instead a single-sided boundary is all that is required. The method is sensitive to attenuation, which makes it difficult to apply to field data. We will show that by using corrections on the attenuated data, we can retrieve the Green’s functions in the subsurface. These results can be visualized in order to see how the wavefield propagates through the subsurface.

scattering into account, is significantly more efficient than modeling the response of the entire medium containing the changed reservoir. This can be particularly attractive for applications in time-lapse full wave form inversion, which requires

repeated modelling of the reflection response.","","en","conference paper","SEG","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:19810c33-dcb1-48de-9eec-87376d1fa01c","http://resolver.tudelft.nl/uuid:19810c33-dcb1-48de-9eec-87376d1fa01c","Full-field multidimensional deconvolution to retrieve body-wave reflections from sparse passive sources","Hartstra, I.E. (TU Delft Applied Geophysics and Petrophysics); Almagro Vidal, C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","Our objective is to complement lithospheric seismic tomography with an interferometric method to retrieve high-resolution reflectivity images from local earthquake recordings. The disadvantage of using local earthquakes for the retrieval of reflected body-waves is their usual sparse distribution. We propose an alternative formulation of passive seismic interferometry by multidimensional deconvolution (MDD) which uses the multiples in the full recordings to compensate for missing illumination angles. This method only requires particle-velocity recordings at the surface from passive transient sources and retrieves body-wave reflection responses without free-surface multiples. We conduct an acoustic modelling experiment to compare this formulation to a previous MDD method and Green’s function retrieval by crosscorrelation for different source distributions. We find that in the case of noise-contaminated recordings obtained under severely limited and irregular illumination conditions, the alternative MDD method introduced here still retrieves the complete reflection response without free-surface multiples where the other interferometric methods break down.","Interferometry; Body waves; Coda waves","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:fd8655a1-35e5-4fa0-803b-361e98b8d5af","http://resolver.tudelft.nl/uuid:fd8655a1-35e5-4fa0-803b-361e98b8d5af","Cross-correlation beamforming","Ruigrok, E.N. (Utrecht University; Royal Netherlands Meteorological Institute); Gibbons, Steven; Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","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 the different sensors. We derive a kernel for beamforming cross-correlated data and call it cross-correlation beamforming (CCBF). We point out that CCBF has slightly better resolution and aliasing characteristics than conventional beamforming. When auto-correlations are added to CCBF, the array response functions are the same as for conventional beamforming. We show numerically that CCBF is more resilient to non-coherent noise. Furthermore, we illustrate that with CCBF individual receiver-pairs can be removed to improve mapping to the slowness domain. An additional flexibility of CCBF is that cross-correlations can be time-windowed prior to beamforming, e.g., to remove the directionality of a scattered wavefield. The observations on synthetic data are confirmed with field data from the SPITS array (Svalbard). Both when beamforming an earthquake arrival and when beamforming ambient noise, CCBF focuses more of the energy to a central beam. Overall, the main advantage of CCBF is noise suppression and its flexibility to remove station pairs that deteriorate the signal-related beampower.","Beamforming; Cross-correlation; Waveform characterization","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:ec71f4f1-35ac-49e6-a1d9-889e36a2f831","http://resolver.tudelft.nl/uuid:ec71f4f1-35ac-49e6-a1d9-889e36a2f831","Application of seismic interferometry by multidimensional deconvolution to ambient seismic noise recorded in Malargüe, Argentina","Weemstra, C. (TU Delft Applied Geophysics and Petrophysics; Utrecht University); Draganov, D.S. (TU Delft Applied Geophysics and Petrophysics); Ruigrok, E.N. (Royal Netherlands Meteorological Institute; Utrecht University); Hunziker, J.W. (University of Lausanne); Gomez, Martin (Comision Nacional de Energia Atomica); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","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 to recordings of ambient seismic noise, mostly surface waves are retrieved. The newly retrieved surface wave responses can be used to extract receiver-receiver phase velocities. These phase velocities often serve as input parameters for tomographic inverse problems. Another application of SI exploits the tempo- ral stability of the multiply scattered arrivals of the newly retrieved surface wave responses. Temporal variations in the stability and/or arrival time of these multiply scattered arrivals can often be linked to temporally varying parameters such as hydrocarbon production and precip- itation. For all applications, however, the accuracy of the retrieved responses is paramount. Correct response retrieval relies on a uniform illumination of the receivers: irregularities in the illumination pattern degrade the accuracy of the newly retrieved responses. In practice, the illumination pattern is often far from uniform. In that case, simple crosscorrelation of separate receiver recordings only yields an estimate of the actual, correct virtual-source response. Re- formulating the theory underlying SI by crosscorrelation as a multidimensional deconvolution (MDD) process, allows this estimate to be improved. SI by MDD corrects for the non-uniform illumination pattern by means of a so-called point-spread function (PSF), which captures the irregularities in the illumination pattern. Deconvolution by this PSF removes the imprint of the irregularities on the responses obtained through simple crosscorrelation. We apply SI by MDD to surface wave data recorded by theMalargue seismic array in western Argentina. The aperture of the array is approximately 60 km and it is located on a plateau just east of the Andean mountain range. The array has a T-shape: the receivers along one of the two lines act as virtual sources whose responses are recorded by the receivers along the other (perpendicular) line.We select time windows dominated by surface wave noise travelling in a favourable direction, that is, traversing the line of virtual sources before arriving at the receivers at which we aim to retrieve the virtual-source responses. These time windows are selected through a frequency-dependent slowness analysis along the two receiver lines. From the selected time windows, estimates of virtual-source responses are retrieved by means of crosscorrelations. Similarly, crosscorrelations between the positions of the virtual sources are computed to build the PSF. We use the PSF to deconvolve the effect of illumination irregularities and the source function from the virtual-source responses retrieved by crosscorrelation. The combined effect of time-window selection and MDD results in more accurate and temporally stable surface wave responses.","Broad-band seismometers; Seismic monitoring and test-ban treaty verification; Surfacewaves and free oscillations; Interfacewaves; Seismic attenuation; Seismic tomography","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "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","abstract","","","","","","","","","","","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: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:8517ffa7-2f28-48f6-bb96-fe93885541fe","http://resolver.tudelft.nl/uuid:8517ffa7-2f28-48f6-bb96-fe93885541fe","Velocity analysis using surface-seismic primaries-only data obtained without removing multiples","Dokter, E. (University of Edinburgh); Meles, G.A. (TU Delft Applied Geophysics and Petrophysics; University of Edinburgh); Curtis, A (University of Edinburgh); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","A number of seismic processing methods, including velocity analysis (Sheriff and Geldart, 1999), make the assumption that recorded waves are primaries - that they have scattered only once (the Born approximation). Multiples then represent a source of coherent noise and must be suppressed to avoid artefacts. There are different approaches to mitigate free surface multiples (see Dragoset et al. (2010) for an overview), but internal multiples still pose a problem and usually cannot be removed without high computational cost or knowledge of the medium. Recently, Marchenko redatuming has been developed to image a medium in the presence of internal multiples (Wapenaar et al., 2014). Using Marchenko redatuming in combination with convolutional interferometry, Meles et al. (2016) have developed a method which allows the construction of a primaries-only data set from existing seismic reflection data and an initial velocity model. The method was proposed for the acoustic case and appears to be robust with respect to even huge inaccuracies in the employed velocity model. In this paper we investigate the impact of such primaries-only data on a simple velocity analysis workflow, as opposed to using the full data set with multiples. We use semblance analysis (Sheriff and Geldart, 1999) and compare the results obtained with three different data sets: the full reflection data with multiples, primaries data calculated with prior knowledge of the subsurface, and primaries data calculated with an entirely incorrect constant velocity model. We then use the velocity models that we construct to perform reverse time migration (RTM) of each of the data sets. We find that the velocities found are robust with respect to errors in the initial model used for Marchenko redatuming, and the method produces good results if non-hyperbolic moveout effects are avoided.","","en","conference paper","EAGE","","","","","","","2017-12-31","","","Applied Geophysics and Petrophysics","","","" "uuid:6f56a5a1-f320-4b0e-8ae7-d4eada60ca08","http://resolver.tudelft.nl/uuid:6f56a5a1-f320-4b0e-8ae7-d4eada60ca08","Theory for Marchenko imaging of marine seismic data with free surface multiple elimination","Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","The theory of data-driven true amplitude migration is presented for multicomponent marine seismic data. The Marchenko scheme is adapted to account for the ghost, free surface and internal multiple effects and works without the need to know the source wavelet. A true amplitude image is formed from the obtained focusing functions without ghost effects and artefacts from free surface and internal multiples. The resulting reflectivity at image times can be input for a final step of full waveform inversion. The numerical example shows the effectiveness of the method in a simple 1D problem.","","en","conference paper","EAGE","","","","","","","2018-01-01","","","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:15993158-7871-409b-bb47-c941ef170a41","http://resolver.tudelft.nl/uuid:15993158-7871-409b-bb47-c941ef170a41","Reflecting boundary conditions for interferometry by multidimensional deconvolution: invited paper","Weemstra, C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van Dalen, K.N. (TU Delft Applied Mechanics)","","2017","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 interferometric applications, however, suffer from the fact that the retrieved virtual-source responses deviate from the true medium responses. The accrued artifacts are often predominantly due to a non-isotropic illumination of the medium of interest, and prohibit accurate interferometric imaging. Recently, it has been shown that illumination-related artifacts can be removed by means of a so-called multidimensional deconvolution (MDD) process. However, The current MDD formulation, and hence method, relies on separation of waves traveling inward and outward through the boundary of the medium of interest. As a consequence, it is predominantly useful when receivers are illuminated from one side only. This puts constraints on the applicability of the current MDD formulation to omnidirectional wavefields. We present a modification of the formulation of the theory underlying SI by MDD. This modification eliminates the requirement to separate inward-and outward propagating wavefields and, consequently, holds promise for the application of MDD to non-isotropic, omnidirectional wavefields","","en","journal article","","","","","","","","2018-05-01","","","Applied Geophysics and Petrophysics","","","" "uuid:65a6e1bc-fd87-4944-82d3-6551b2d973a2","http://resolver.tudelft.nl/uuid:65a6e1bc-fd87-4944-82d3-6551b2d973a2","Obtaining local reflectivity at two-way travel time by filtering acoustic reflection data","Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Zhang, L. (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","A modified implementation of Marchenko redatuming leads to a filter that removes internal multiples from reflection data. It produces local reflectivity at two-way travel time. The method creates new primary reflections resulting from emitted events that eliminate internal multiples. We call these non-physical

primaries and their presence is a disadvantage. The advantage is that the filter is model free. We give the 3D filter and demonstrate with 1D arguments that starting the focusing wavefield with a unit impulse at zero time, while focusing below the bottom reflector, is the choice that leads to a model free implementation. The starting impulse generates the reflection data. Every later emitted pulse eliminates an internal multiple somewhere in the model and helps removing the transmission

amplitude effects in a physical primary. We show that

the amplitude of the non-physical primaries are a product of

three reflections, making them generally smaller than those of

the physical primaries. A 2D modeled shotgather at different

stages of filtering the data shows that the filter works well.","","en","conference paper","SEG","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","","" "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","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:5bf1b74f-1582-40e0-bdc3-9ec696cdb67d","http://resolver.tudelft.nl/uuid:5bf1b74f-1582-40e0-bdc3-9ec696cdb67d","Deep ocean sound speed characteristics passively derived from the ambient acoustic noise field","Evers, L.G. (TU Delft Applied Geophysics and Petrophysics; Royal Netherlands Meteorological Institute); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Heaney, KD (Ocean Acoustical Services and Instrumentation Systems); Snellen, M. (TU Delft Aircraft Noise and Climate Effects)","","2017","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 acoustic noise field can be used instead of deterministic transient signals. In this study the acoustic velocity, and hence the temperature, is derived in an interferometric approach from hydrophone array recordings. The arrays were separated by over 125 km, near Ascension Island in the Atlantic Ocean, at a depth of 850 m. Furthermore, the dispersive characteristics of the deep ocean sound channel are resolved based on the retrieved lag times for different modes. In addition, it is shown how the resolution of the interferometric approach can be increased by cross correlating array beams rather than recordings from single-sensor pairs. The observed acoustic lag times between the arrays corresponds well to modelled values, based on full-wave modelling through best-known oceanic models.","Atlantic Ocean; Interferometry; Acoustic properties; Wave propagation","en","journal article","","","","","","","","","","","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: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","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","","" "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","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:ef4dd296-1e64-42fa-9c8a-56e2bb515b9a","http://resolver.tudelft.nl/uuid:ef4dd296-1e64-42fa-9c8a-56e2bb515b9a","Reflecting boundary conditions for interferometry by multidimensional deconvolution.","Weemstra, C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); van Dalen, K.N. (TU Delft Dynamics of Structures)","","2017","Session 1pUWc: Underwater Acoustics: Topics in Underwater Acoustics (Poster Session)","","en","abstract","","","","","","","","","","","","","","" "uuid:95ea33ec-4f45-4b19-9a85-fbef153ecb51","http://resolver.tudelft.nl/uuid:95ea33ec-4f45-4b19-9a85-fbef153ecb51","Elastodynamic single-sided homogeneous Green's function representation: Theory and examples","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Reinicke Urruticoechea, C. (TU Delft Applied Geophysics and Petrophysics)","","2017","The homogeneous Green’s function is the Green’s function minus its timereversal. Many wavefield imaging applications make use of the homogeneous Green’s function in form of a closed boundary integral. Wapenaar et al. (2016a) derived an accurate single-sided homogeneous Green’s function representation that only requires sources/receivers on an open boundary. In this abstract we will present a numerical example of elastodynamic singlesided homogeneous Green’s function representation using a 2D laterally invariant medium. First, we will outline the theory of the single-sided homogeneous Green’s function representation. Second, we will show numerical results for the elastodynamic case.","","en","conference paper","EAGE","","","","","","","2018-01-01","","","","","","" "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:644e9cc5-1e9a-43ec-b7cf-7f96fc3557bf","http://resolver.tudelft.nl/uuid:644e9cc5-1e9a-43ec-b7cf-7f96fc3557bf","A single-sided representation for the homogeneous Green's function of a unified scalar wave equation","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2017","","","en","journal article","","","","","","","","2017-12-31","","","Applied Geophysics and Petrophysics","","","" "uuid:ee0b3190-beb4-4de6-bdc8-2a25c569dbbb","http://resolver.tudelft.nl/uuid:ee0b3190-beb4-4de6-bdc8-2a25c569dbbb","A lossless earth Green's function representation between any two subsurface points from surface reflection GPR data","Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2017","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 computed. With the aid of the Green's functions of the virtual vertical radar profiles these focusing wavefields are then used to compute the Green's function between any two points in the subsurface. One point is a virtual receiver and the other point is a virtual source. Virtual radar images can be created as well as the whole time evolution of the radar wave field throughout the subsurface generated by any subsurface virtual source. We show with a numerical example that the method works well in a one-dimensional configuration.","3D GPR; autofocusing; interferometry; virtual receiver; virtual source","en","conference paper","Institute of Electrical and Electronics Engineers Inc.","","","","","","","","","","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: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:201a0468-4228-4f75-a579-a29f62b825f2","http://resolver.tudelft.nl/uuid:201a0468-4228-4f75-a579-a29f62b825f2","Q‐factor Estimation and Redatuming in a Lossy Medium Using the Marchenko Equation","Alkhimenkov, Y.; Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2018","Marchenko Imaging is a new technology in geophysics, which enables us to retrieve Green's functions at any point in the subsurface having only reflection data. One of the assumptions of the Marchenko method is that the medium is lossless. One way to circumvent this assumption is to find a compensation parameter for the lossy reflection series so that the lossless Marchenko scheme can be applied. The main goals of this work are to: [1] use the Marchenko equation to estimate the attenuation in the subsurface, [2] find a compensation

parameter for the lossy reflection series so that the lossless Marchenko scheme can be applied. We propose a novel approach which makes it possible to calculate an effective temporal Q‐factor of the medium between a virtual source in the subsurface and receivers at the surface. This method is based on the minimization of the artefacts produced by the lossless Marchenko scheme. Artefacts have a very specific behavior: if the input data to the Marchenko equation are over‐ or under‐ compensated, the resulting artefacts will have an opposite polarity. Thus, they can be recognized. This approach is supported by a synthetic example for a 1D acoustic medium without a free surface.","","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.","","2018-12-14","","","Applied Geophysics and Petrophysics","","","" "uuid:ce065c7e-0042-4bb5-9a33-10950d2d0343","http://resolver.tudelft.nl/uuid:ce065c7e-0042-4bb5-9a33-10950d2d0343","Acoustic directional snapshot wavefield decomposition","Holicki, M.E. (TU Delft Applied Geophysics and Petrophysics); Drijkoningen, G.G. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2018","Up–down wavefield decomposition is effectuated by a scaled addition or subtraction of the pressure and vertical particle velocity, generally on horizontal or vertical surfaces, and works well for data given on such surfaces. The method, however, is not applicable to decomposing a wavefield when it is given at one instance in time, i.e. on snapshots. Such situations occur when a wavefield is modelled with methods like finite-difference techniques, for the purpose of, for example, reverse time migration, where the entire wavefield is determined per time instance. We present an alternative decomposition method that is exact when working on snapshots of an acoustic wavefield in a homogeneous medium, but can easily be approximated to heterogeneous media, and allows the wavefield to be decomposed in arbitrary directions. Such a directional snapshot wavefield decomposition is achieved by recasting the acoustic system in terms of the time derivative of the pressure and the vertical particle velocity, as opposed to the vertical derivative in up–down decomposition for data given on a horizontal surface. As in up–down decomposition of data given at a horizontal surface, the system can be eigenvalue decomposed and the inverse of the eigenvector matrix decomposes the wavefield snapshot into fields of opposite directions, including up–down decomposition. As the vertical particle velocity can be rotated at will, this allows for decomposition of the wavefield into any spatial direction; even spatially varying directions are possible. We show the power and effectiveness of the method by synthetic examples and models of increasing complexity.","Acoustics; Modelling; Multicomponent; Seismics","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:7f83193e-43f0-4d35-a334-98e56c0e73fc","http://resolver.tudelft.nl/uuid:7f83193e-43f0-4d35-a334-98e56c0e73fc","A single-sided representation for the homogeneous Green's function, accounting for all multiples","Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (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)","","2018","Marchenko imaging is a novel imaging technique that is capable to retrieve images from single-sided reflection measurements free of artefacts related to internal multiples (e.g. Behura et al., 2014; Broggini et al., 2012). An essential ingredient of Marchenko imaging is the so-called focusing function which can

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","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:dfe1055f-645e-4753-96df-c49ba4df838d","http://resolver.tudelft.nl/uuid:dfe1055f-645e-4753-96df-c49ba4df838d","Passive body-wave interferometric imaging with directionally constrained migration","Almagro Vidal, C. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging); Verdel, Arie (TNO); Hartstra, I.E. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2018","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 availability of passive recordings from sufficient sources in the subsurface. Ideally, these sources should be homogeneously distributed, which is unlikely to happen in practical applications. Incomplete source distributions result in the retrieval of inaccurate reflection responses, containing artefacts which can disturb the interferometric imaging process. We propose an alternative imaging method for passive data based on illumination diagnosis and directionally constrained migration. In this method, passive responses from single transient sources are cross-correlated individually, and the dominant radiation direction from each virtual source is estimated. The correlated responses are imaged individually, thereby limiting the source wavefield to the dominant radiation direction of the virtual source. This constraint enables the construction of accurate images from individual sources with a significantly reduced amount of migrated interferometric artefacts. We also show that the summation of all individual imaging results improves the subsurface image by constructive interference, while migrated crosstalk and artefacts experience cancellation. This process, called Image Interferometry, shows that in case of limited subsurface illumination the interferometric integration can be applied in the image domain rather than in the virtual reflection-response domain, thus eliminating the need for the retrieval of the reflection response as an intermediate step.","Seismic Interferometry; Body waves; Crustal imaging","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:013a0e81-3a84-4013-975c-4a2624fb4b0e","http://resolver.tudelft.nl/uuid:013a0e81-3a84-4013-975c-4a2624fb4b0e","Virtual seismology: from hydrocarbon reservoir imaging to induced earthquake monitoring","Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); Staring, M. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics)","","2018","Recent developments in exploration seismology have enabled the creation of virtual sources and/or virtual receivers in the subsurface from reflection measurements at the earth's surface. Unlike in seismic interferometry, no physical instrument (receiver or source) is needed at the position of the virtual source or receiver. Moreover, no detailed knowledge of the subsurface parameters and structures is required: a smooth velocity model suffices. Yet, the responses to the virtual sources, observed by the virtual receivers, fully account for multiple scattering. This new methodology, which we call virtual seismology, has led to a breakthrough in hydrocarbon reservoir imaging, as is demonstrated in a companion paper (Staring et al., Marchenko redatuming for multiple prediction and removal in situations with a complex overburden). The aim of the present paper is to discuss applications of virtual seismology beyond exploration seismology, in particular induced earthquake monitoring, and to highlight the connections between these applications. The ability to retrieve the entire wave field between (virtual or real) sources and receivers anywhere in the subsurface, without needing a detailed subsurface model, has large potential for monitoring induced seismicity, characterizing the source properties (such as the moment tensor of extended sources along a fault plane), and forecasting the response to potential future induced earthquakes. This will be demonstrated with numerical models and preliminary real-data results.","","en","conference paper","","","","","","Abstract S53A-03 presented at 2018 Fall Meeting, AGU, Washington, D.C., 10-14 Dec. Session: S53A On the Symbiosis Between Fundamental and Exploration Geophysics I","","2019-06-14","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:69b76fb7-85ff-46df-9865-2375ebda01de","http://resolver.tudelft.nl/uuid:69b76fb7-85ff-46df-9865-2375ebda01de","Artefact-Free Imaging by a Revised Marchenko Scheme","Zhang, L. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging)","","2018","A revised Marchenko scheme that avoids the need to compute the Green’s function is presented for artefact-free image of the subsurface with single-sided reflection response as input. The initial downgoing Green’s function which can be modelled from a macro model is needed for solving the revised Marchenko equations instead of its inverse. The retrieved upgoing focusing function can be correlated with the modelled initial downgoing Green’s function to image the medium without artefacts. The numerical example shows the effectiveness of the revised scheme in a 2D layered case.","","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.","","2018-12-14","","","","","","" "uuid:74b21e40-6dfc-4ff4-be4d-dffdc8ffba34","http://resolver.tudelft.nl/uuid:74b21e40-6dfc-4ff4-be4d-dffdc8ffba34","Artifact-free reverse time migration","Zhang, L. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (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)","","2018","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 wavefield-extrapolation operator as initial estimate for retrieving the upgoing focusing function. Then, the retrieved upgoing focusing function can be used to directly image the medium by correlating it with the standard wavefieldextrapolation operator. This imaging scheme can be seen as an artifact-free RTM scheme with two terms. The first term gives the conventional RTM image with the wrong amplitude and artifacts due to internal multiple reflections. The second term gives a correction image that can be used to correct the amplitude and remove artifacts in the image generated by the first term. We evaluated the success of the method with a 2D numerical example.","","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:971090a1-d8f6-4e13-96cc-4f022707d87a","http://resolver.tudelft.nl/uuid:971090a1-d8f6-4e13-96cc-4f022707d87a","Source-receiver Marchenko redatuming on field data using an adaptive double-focusing method","Staring, M. (TU Delft Applied Geophysics and Petrophysics); Pereira, Roberto (CGG, Rio de Janeiro); Douma, Huub (CGG, Rio de Janeiro); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2018","We have developed an adaptive double-focusing method that is specifically designed for the field-data application of source-receiver Marchenko redatuming. Typically, the single-focusing Marchenko method is combined with a multidimensional deconvolution (MDD) to achieve redatuming. Our method replaces the MDD step by a second focusing step that naturally complements the single-focusing Marchenko method. Instead of performing the MDD method with the directionally decomposed Green's functions that result from single-focusing, we now use the retrieved upgoing Green's function and the retrieved downgoing focusing function to obtain a redatumed reflection response in the physical medium. Consequently, we only remove the strongest overburden effects instead of removing all of the overburden effects. However, the gain is a robust method that is less sensitive to imperfections in the data and a sparse acquisition geometry than the MDD method. In addition, it is computationally much cheaper, more straightforward to implement, and it can be parallelized over pairs of focal points, which makes it suitable for application to large data volumes. We evaluate the successful application of our method to 2D field data of the Santos Basin.","Adaptive subtraction; Autofocusing; Datuming; Internal multiples; Subsalt","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:8511a3bc-e21c-4993-8438-af7e39c77388","http://resolver.tudelft.nl/uuid:8511a3bc-e21c-4993-8438-af7e39c77388","Marchenko redatuming for multiple prediction and removal in situations with a complex overburden","Staring, M. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2018","Internal multiples can create severe artefacts in seismic imaging, especially when our zone of interest is overlain by a complex overburden. These artefacts can mask structures, which has a strong effect on the interpretation of the image. Therefore, multiple prediction and removal is of significant importance for correct imaging and interpretation in settings with a complex overburden.

We propose an adaptive double-focusing method to predict and subtract the internal multiples that were generated in the overburden. This method is a form of the Marchenko method, that can retrieve the directionally-decomposed Green's functions between virtual sources and virtual receivers anywhere inside the subsurface. The retrieved Green's functions contain all orders of multiple scattering. The method only requires the single-sided reflection response and a smooth velocity model as input. Instead of conventional imaging methods, that assume that the wavefield only consists of single-scattered waves (and thus create imaging artefacts when multiple scattering is present), we now use the multiple-scattered Marchenko wavefields for correct redatuming and imaging.

We apply our method to 2D and 3D field data that were recorded in settings where imaging and interpretation is hindered by a complex overburden. First, we create virtual sources and virtual receivers directly above our zone of interest. Next, we use the retrieved Marchenko wavefields to predict and subtract the internal multiples that were generated in the overburden. Masked structures become visible after multiple removal, which significantly improves the geological interpretability. Therefore, we conclude that the adaptive double-focusing method (Marchenko redatuming) is capable of correctly predicting and removing internal multiples generated in the overburden.","","en","abstract","","","","","","Abstract S24A-03 presented at 2018 Fall Meeting, AGU, Washington, D.C., 10-14 Dec. Session: [S24A] Frontiers in Theoretical and Computational Seismology I","","2019-06-11","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:3091b118-e955-4727-9127-79a34d026cd8","http://resolver.tudelft.nl/uuid:3091b118-e955-4727-9127-79a34d026cd8","A tour of Marchenko redatuming: Focusing the subsurface wavefield","Cui, Tianci (Schlumberger Gould Research); Vasconcelos, Ivan (Utrecht University); Manen, Dirk Jan Van (Institute of Geophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2018","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 in a truncated version of the actual medium, the Marchenko focusing functions focus the wavefields at the virtual source location and are responsible for the subsequent retrieval of the downgoing and upgoing components of the medium's impulse response. In real seismic exploration, where we have no access to the truncated medium, we solve the coupled Marchenko equations by iterative substitution, relying on the causality relations between the focusing functions and the desired Green's functions along with an initial estimate of the downgoing focusing function. We show that the amplitude accuracy of the initial focusing function influences that of the retrieved Green's functions. During each iteration, propagating an updated focusing function into the actual medium can be approximated by explicit convolution with the broadband reflection seismic data after appropriate processing, which acts as a proxy for the true medium's reflection response.","Acoustic; Autofocusing; Internal multiples; Processing","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:ec82b4a8-3f09-45c2-9506-1453e3a8d6fe","http://resolver.tudelft.nl/uuid:ec82b4a8-3f09-45c2-9506-1453e3a8d6fe","Fast nonrecursive 1D inversion by filtering acoustic-reflection data","Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Treitel, Sven (Tridekon)","","2018","We derive a fast acoustic inversion method for a piecewise homogeneous horizontally layered medium. The method obtains medium parameters from the reflection response. The method can be implemented to obtain the parameters on either side of a reflector at an arbitrary depth. Three processing steps lead to the inversion result. First, we solve a modified Marchenko type equation to obtain a focusing wavefield. We then apply wavefield continuation across a reflecting boundary to the focusing wavefield and retrieve the reflection coefficient of a reflector as a function of horizontal slowness. Finally, we use the reflection coefficient to obtain the velocities and the ratio of the densities above and below the reflector. Because the two-way traveltime difference of the primary reflection and the one above it becomes known during the process, the thickness of the layer above the reflector is also found. The method can be applied multiple times in different zones, or recursively in a target zone without having to solve more Marchenko type equations. The numerical example illustrates that the method works well on modeled data without the need for a priori model information.","inversion; processing; acoustic","en","conference paper","SEG","","","","","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.","","2019-04-19","","","Applied Geophysics and Petrophysics","","","" "uuid:324bfb26-265a-4299-b4e8-c2d55be43643","http://resolver.tudelft.nl/uuid:324bfb26-265a-4299-b4e8-c2d55be43643","Retrieval of Elastodynamic Reflections From Passive Double-Couple Recordings","Hartstra, I.E. (TU Delft Applied Geophysics and Petrophysics); Almagro Vidal, C.; Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2018","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 source distributions, scattering (in case of suboptimal illumination), and complex source mechanisms can significantly disturb the retrieval of Green's function approximations by conventional SI methods. We introduce SI by full-field multidimensional deconvolution (MDD) for elastodynamic wavefields as an alternative method to obtain body wave Green's functions under those typical circumstances. The advantage of this method compared to other MDD methods is that the kernel of its governing equation is exact. This alternative formulation of the kernel pertains to several advantages: the solution is less sensitive to artifacts and utilizes the free-surface multiples in the data to estimate primary reflections. Moreover, the point spread function of the full-field MDD method corrects more affectively for irregular illumination because it also addresses irregularities caused by scattering inside the medium. In order to compare full-field MDD to existing SI methods, we model synthetic earthquake recordings in a subduction zone setting using an elastodynamic finite-difference scheme with double couples of different orientations and peak frequencies. Our results show that SI by cross correlation suffers most under these circumstances. Higher-quality reflections are obtained by the MDD methods, of which full-field MDD involves the most stable inversion, and its results are least contaminated by artifacts.","body waves; elastodynamic; multidimensional deconvolution; reflections; seismic interferometry","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:5c2a435d-5004-455f-9ee3-4afcedc50283","http://resolver.tudelft.nl/uuid:5c2a435d-5004-455f-9ee3-4afcedc50283","Locating scatterers while drilling using seismic noise due to tunnel boring machine","Harmankaya, U (Istanbul Technical University); Kaslilar, A. (Istanbul Technical University); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); Draganov, D.S. (TU Delft Applied Geophysics and Petrophysics)","","2018","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 geological and geophysical investigations, which are limited by location and resolution, respectively. For detailed information about the structures ahead of the tunnel face, geophysical methods are applied during the tunnel-drilling activity. We present a method inspired by seismic interferometry and ambient-noise correlation that can be used for detecting scatterers, such as boulders and cavities, ahead of a tunnel while drilling. A similar method has been proposed for active-source seismic data and validated using laboratory and field data. Here, we propose to utilize the seismic noise generated by a Tunnel Boring Machine (TBM), and recorded at the surface. We explain our method at the hand of data from finite-difference modelling of noise-source wave propagation in a medium where scatterers are present. Using the modelled noise records, we apply cross-correlation to obtain correlation gathers. After isolating the scattered arrivals in these gathers, we cross-correlate again and invert for the correlated traveltime to locate scatterers. We show the potential of the method for locating the scatterers while drilling using noise records due to TBM.","Body waves; Finite-difference modelling; Locating scatterers; Seismic-noise correlation; Traveltime inversion; Tunnel seismic-while-drilling","en","journal article","","","","","","","","2020-04-05","","","Applied Geophysics and Petrophysics","","","" "uuid:13bf575c-66d4-4321-9329-29e99403660e","http://resolver.tudelft.nl/uuid:13bf575c-66d4-4321-9329-29e99403660e","Marchenko-Based Target Replacement, Accounting for All Orders of Multiple Reflections","Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Staring, M. (TU Delft Applied Geophysics and Petrophysics)","","2018","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 target zone. The proposed process consists of two main steps. In the first step, the response of the original target zone is removed from the reflection response, using the Marchenko method. In the second step, the modelled response of a new target zone is inserted between the overburden and underburden responses. The method fully accounts for all orders of multiple scattering and, in the elastodynamic case, for wave conversion. For monitoring purposes, only the second step needs to be repeated for each target-zone model. Since the target zone covers only a small part of the entire medium, the proposed method is much more efficient than repeated modelling of the entire reflection response.","multiples; representations; seismic; time-lapse","en","journal article","","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:f47e0797-e53d-43e5-afbc-88d7316f3118","http://resolver.tudelft.nl/uuid:f47e0797-e53d-43e5-afbc-88d7316f3118","Virtual plane-wave imaging via Marchenko redatuming","Meles, G.A. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics)","","2018","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 similarly to standard migration methods, Marchenko redatuming only requires an estimate of the direct wave from the virtual source (or to the virtual receiver), illumination from only one side of the medium and no physical sources (or receivers) inside the medium. In this contribution we consider a different time-focusing condition within the frame of Marchenko redatuming that leads to the retrieval of virtual plane-wave responses. As a result, it allows multiple-free imaging using only a 1-D sampling of the targeted model at a fraction of the computational cost of standard Marchenko schemes. The potential of the new method is demonstrated on 2-D synthetic models.","Controlled source seismology; Seismic interferometry; Wave scattering and diffraction","en","journal article","","","","","","","","","","","Applied Geophysics and Petrophysics","","","" "uuid:2edcfd29-45e8-48e5-8ba3-4201fa8d5069","http://resolver.tudelft.nl/uuid:2edcfd29-45e8-48e5-8ba3-4201fa8d5069","Virtual acoustics in inhomogeneous media with single-sided access","Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (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); Verschuur, D.J. (TU Delft ImPhys/Acoustical Wavefield Imaging)","","2018","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 use of complex focusing functions to create virtual acoustic sources and virtual receivers inside an inhomogeneous medium with single-sided access. The retrieved virtual acoustic responses between those sources and receivers mimic the complex propagation and multiple scattering paths of waves that would be ignited by physical sources and recorded by physical receivers inside the medium. The possibility to predict complex virtual acoustic responses between any two points inside an inhomogeneous medium, without needing a detailed model of the medium, has large potential for holographic imaging and monitoring of objects with single-sided access, ranging from photoacoustic medical imaging to the monitoring of induced-earthquake waves all the way from the source to the earth's surface.","","en","journal article","","","","","","","","","","","ImPhys/Acoustical Wavefield Imaging","","","" "uuid:3fbcd73e-0bad-4d30-8f42-143dfbc431eb","http://resolver.tudelft.nl/uuid:3fbcd73e-0bad-4d30-8f42-143dfbc431eb","Green's theorem in seismic imaging across the scales","Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics)","","2019","The earthquake seismology and seismic exploration communities have developed a variety of seismic imaging methods for passive- and active-source data. Despite the seemingly different approaches and underlying principles, many of those methods are based in some way or another on Green's theorem. The aim of this paper is to discuss a variety of imaging methods in a systematic way, using a specific form of Green's theorem (the homogeneous Green's function representation) as a common starting point. The imaging methods we cover are time-reversal acoustics, seismic interferometry, back propagation, source–receiver redatuming and imaging by double focusing. We review classical approaches and discuss recent developments that fully account for multiple scattering, using the Marchenko method. We briefly indicate new applications for monitoring and forecasting of responses to induced seismic sources, which are discussed in detail in a companion paper.","","en","journal article","","","","","","","","","","","","","","" "uuid:c9de6483-2a05-4f05-a25f-cba2cf92ddb6","http://resolver.tudelft.nl/uuid:c9de6483-2a05-4f05-a25f-cba2cf92ddb6","Elastodynamic single-sided homogeneous Green’s function representation: Theory and numerical examples","Reinicke Urruticoechea, C. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2019","The homogeneous Green’s function is the difference between an impulse response and its time-reversal. According to existing representation theorems, the homogeneous Green’s function associated with source–receiver pairs inside a medium can be computed from measurements at a boundary enclosing the medium. However, in many applications such as seismic imaging, time-lapse monitoring, medical imaging, non-destructive testing, etc., media are only accessible from one side. A recent development of wave theory has provided a representation of the homogeneous Green’s function in an elastic medium in terms of wavefield recordings at a single (open) boundary. Despite its single-sidedness, the elastodynamic homogeneous Green’s function representation accounts for all orders of scattering inside the medium. We present the theory of the elastodynamic single-sided homogeneous Green’s function representation and illustrate it with numerical examples for 2D laterally-invariant media. For propagating waves, the resulting homogeneous Green’s functions match the exact ones within numerical precision, demonstrating the accuracy of the theory. In addition, we analyse the accuracy of the single-sided representation of the homogeneous Green’s function for evanescent wave tunnelling.","Elastic; Interferometry; Internal multiples; Layered; Numerical","en","journal article","","","","","","Accepted Author Manuscript","","2021-04-17","","","","","","" "uuid:eb49b58e-7917-4bd2-a89d-8e86a61009a9","http://resolver.tudelft.nl/uuid:eb49b58e-7917-4bd2-a89d-8e86a61009a9","Unified matrix-vector wave equation, reciprocity and representations","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2019","The matrix-vector wave equation is a compact first-order differential equation. It was originally used for the analysis of elastodynamic plane waves in laterally invariant media. It has been extended by various authors for laterally varying media. Other authors derived a similar formalism for other wave phenomena. This paper starts with a unified formulation of the matrix-vector wave equation for 3-D inhomogeneous, dissipative media. The wave vector, source vector and operator matrix are specified in the appendices for acoustic, quantum mechanical, electromagnetic, elastodynamic, poroelastodynamic, piezoelectric and seismoelectric waves. It is shown that the operator matrix obeys unified symmetry relations for all these wave phenomena. Next, unified matrix-vector reciprocity theorems of the convolution and correlation type are derived, utilizing the symmetry properties of the operator matrix. These theorems formulate mathematical relations between two wave states in the same spatial domain. A unified wavefield representation is obtained by replacing one of the states in the convolution-type reciprocity theorem by a Green's state. By replacing both states in the correlation-type reciprocity theorem by Green's states, a unified representation of the homogeneous Green's matrix is obtained. Applications of the unified reciprocity theorems and representations for forward and inverse wave problems are briefly indicated.","Electromagnetic theory; Theoretical seismology; Wave propagation","en","journal article","","","","","","","","","","","","","","" "uuid:c8f3dfa3-88cb-4ada-b604-fa1cb6c43fec","http://resolver.tudelft.nl/uuid:c8f3dfa3-88cb-4ada-b604-fa1cb6c43fec","Application of seismic interferometry by multidimensional deconvolution to earthquakes data recorded in Malargue, Argentina","Shirmohammadi, F. (University of Tehran); Weemstra, C. (TU Delft Applied Geophysics and Petrophysics); Draganov, D.S. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics)","","2019","","","en","poster","","","","","","","","","","","","","","" "uuid:386ff8b1-0720-49e2-8425-3de163aea36f","http://resolver.tudelft.nl/uuid:386ff8b1-0720-49e2-8425-3de163aea36f","Reciprocity-based passive monitoring with individual sources","Almagro Vidal, C. (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)","","2019","Time-lapse changes in the subsurface can be analyzed by comparing seismic reflection data from two different states, one serving as the base survey and the second as the monitor survey. Conventionally, reflection data are acquired by placing active seismic sources at the acquisition surface. Alternatively, these data can be acquired from passive sources in the subsurface, using seismic interferometry (SI). Unfortunately, the reflection responses as retrieved by SI inherit an imprint of the passive-source distribution; therefore, monitoring with SI requires high passive-source repeatability, which is very often not achievable in practice.We have developed an alternative by using active seismic data for the base survey and a single passive source (e.g., a seismic tremor produced by induced seismicity) for the monitor survey. By constraining the source-radiation pattern of the (active) base survey according to the characteristics of the (passive) monitor survey, we succeed in extracting the time-lapse response in the image domain. We tested our method with numerically modeled data.","","en","journal article","","","","","","Accepted Author Manuscript","","","","","","","","" "uuid:85aa81cb-4cf0-48c7-a9fc-95f6cef248bf","http://resolver.tudelft.nl/uuid:85aa81cb-4cf0-48c7-a9fc-95f6cef248bf","Transmission compensated primary reflection retrieval in the data domain and consequences for imaging","Zhang, L. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics)","","2019","We have developed a scheme that retrieves primary reflections in the two-way traveltime domain by filtering the data. The data have their own filter that removes internal multiple reflections, whereas the amplitudes of the retrieved primary reflections are compensated for two-way transmission losses. Application of the filter does not require any model information. It consists of convolutions and correlations of the data with itself. A truncation in the time domain is applied after each convolution or correlation. The retrieved data set can be used as the input to construct a better velocity model than the one that would be obtained by working directly with the original data and to construct an enhanced subsurface image. Two 2D numerical examples indicate the effectiveness of the method. We have studied bandwidth limitations by analyzing the effects of a thin layer. The presence of refracted and scattered waves is a known limitation of the method, and we studied it as well. Our analysis indicates that a thin layer is treated as a more complicated reflector, and internal multiple reflections related to the thin layer are properly removed. We found that the presence of refracted and scattered waves generates artifacts in the retrieved data.","acoustic; internal multiples","en","journal article","","","","","","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.","","2019-10-26","","","","","","" "uuid:630be8fb-2a14-43f9-a5a6-af1ff80253f7","http://resolver.tudelft.nl/uuid:630be8fb-2a14-43f9-a5a6-af1ff80253f7","An acoustic imaging method for layered non-reciprocal media","Wapenaar, C.P.A. (TU Delft ImPhys/Acoustical Wavefield Imaging; TU Delft Applied Geophysics and Petrophysics); Reinicke Urruticoechea, C. (TU Delft Applied Geophysics and Petrophysics)","","2019","Given the increasing interest for non-reciprocal materials, we propose a novel acoustic imaging method for layered non-reciprocal media. The method we propose is a modification of the Marchenko imaging method, which handles multiple scattering between the layer interfaces in a data-driven way. We start by reviewing the basic equations for wave propagation in a nonreciprocal medium. Next, we discuss Green’s functions, focusing functions, and their mutual relations, for a non-reciprocal horizontally layered medium. These relations form the basis for deriving the modified Marchenko method, which retrieves the wave field inside the non-reciprocal medium from reflection measurements at the boundary of the medium. With a numerical example we show that the proposed method is capable of imaging the layer interfaces at their correct positions, without artefacts caused by multiple scattering.","","en","journal article","","","","","","Accepted Author Manuscript","","2020-03-08","","","","","","" "uuid:a06e8d0f-20d8-45ed-8dda-a3aa8512fadf","http://resolver.tudelft.nl/uuid:a06e8d0f-20d8-45ed-8dda-a3aa8512fadf","Wavefield finite time focusing with reduced spatial exposure","Meles, G.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft ImPhys/Acoustical Wavefield Imaging); van Dongen, K.W.A. (TU Delft ImPhys/Acoustical Wavefield Imaging); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics; TU Delft ImPhys/Acoustical Wavefield Imaging)","","2019","Wavefield focusing is often achieved by time-reversal mirrors, where wavefields emitted by a source located at the focal point are evaluated at a closed boundary and sent back, after time-reversal, into the medium from that boundary. Mathematically, time-reversal mirrors are derived from closed-boundary integral representations of reciprocity theorems. In heterogeneous media, time-reversal focusing theoretically involves in- and output signals that are infinite in time and the resulting waves propagate through the entire medium. Recently, integral representations have been derived for single-sided wavefield focusing. Although the required input signals for this approach are finite in time, the output signals are not and, similar to time-reversal mirroring, the resulting waves propagate through the entire medium. Here, an alternative solution for double-sided wavefield focusing is derived. This solution is based on an integral representation where in- and output signals are finite in time, and where the energy of the waves propagating in the layer embedding the focal point is smaller than with time-reversal focusing. The potential of the proposed method is explored with numerical experiments involving a head model consisting of a skull enclosing a brain.","","en","journal article","","","","","","Accepted Author Manuscript","","2019-12-18","","","","","","" "uuid:925d79da-5620-4234-9ef4-b2b7800b0200","http://resolver.tudelft.nl/uuid:925d79da-5620-4234-9ef4-b2b7800b0200","Monitoring of induced distributed double-couple sources using Marchenko-based virtual receivers","Brackenhoff, J.A. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics; TU Delft ImPhys/Acoustical Wavefield Imaging)","","2019","We aim to monitor and characterize signals in the subsurface by combining these passive signals with recorded reflection data at the surface of the Earth. To achieve this, we propose a method to create virtual receivers from reflection data using the Marchenko method. By applying homogeneous Green's function retrieval, these virtual receivers are then used to monitor the responses from subsurface sources. We consider monopole point sources with a symmetric source signal, for which the full wave field without artifacts in the subsurface can be obtained. Responses from more complex source mechanisms, such as double-couple sources, can also be used and provide results with comparable quality to the monopole responses. If the source signal is not symmetric in time, our technique based on homogeneous Green's function retrieval provides an incomplete signal, with additional artifacts. The duration of these artifacts is limited and they are only present when the source of the signal is located above the virtual receiver. For sources along a fault rupture, this limitation is also present and more severe due to the source activating over a longer period of time. Part of the correct signal is still retrieved, as is the source location of the signal. These artifacts do not occur in another method that creates virtual sources as well as receivers from reflection data at the surface. This second method can be used to forecast responses to possible future induced seismicity sources (monopoles, double-couple sources and fault ruptures). This method is applied to field data, and similar results to the ones on synthetic data are achieved, which shows the potential for application on real data signals.","","en","journal article","","","","","","","","","","","","","","" "uuid:7a44427e-fea6-49c2-bc56-0b2848b7a2a6","http://resolver.tudelft.nl/uuid:7a44427e-fea6-49c2-bc56-0b2848b7a2a6","Unified wave field retrieval and imaging method for inhomogeneous non-reciprocal media","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics; TU Delft ImPhys/Acoustical Wavefield Imaging); Reinicke Urruticoechea, C. (TU Delft Applied Geophysics and Petrophysics)","","2019","Acoustic imaging methods often ignore multiple scattering. This leads to false images in cases where multiple scattering is strong. Marchenko imaging has recently been introduced as a data-driven way to deal with internal multiple scattering. Given the increasing interest in non-reciprocal materials, both for acoustic and electromagnetic applications, a modification to the Marchenko method is proposed for imaging such materials. A unified wave equation is formulated for non-reciprocal materials, exploiting the similarity between acoustic and electromagnetic wave phenomena. This unified wave equation forms the basis for deriving reciprocity theorems that interrelate wave fields in a non-reciprocal medium and its complementary version. Next, these theorems are reformulated for downgoing and upgoing wave fields. From these decomposed reciprocity theorems, representations of the Green's function inside the non-reciprocal medium are derived in terms of the reflection response at the surface and focusing functions inside the medium and its complementary version. These representations form the basis for deriving a modified version of the Marchenko method to retrieve the wave field inside a non-reciprocal medium and to form an image, free from artefacts related to multiple scattering. The proposed method is illustrated at the hand of the numerically modeled reflection response of a horizontally layered medium.","","en","journal article","","","","","","Accepted Author Manuscript","","2020-01-31","","","","","",""