; NOOh+'0HP
$TU Delft Repository search results0TU Delft Repository search results (max. 1000)TU Delft LibraryTU Delft Library@jaȄ@jaȄ՜.+,0HPX`hp
x
WorksheetFeuilles de calcul
B=%r8X"1Calibri1Calibri1Calibri1
Calibri 83ffff̙̙3f3fff3f3f33333f33333.==TU Delft Repositoryg :uuidrepository linktitleauthorcontributorpublication yearabstract
subject topiclanguagepublication type publisherisbnissnpatent
patent statusbibliographic noteaccess restrictionembargo datefaculty
departmentresearch group programmeprojectcoordinates)uuid:85aa81cb4cf048c7a9fc95f6cef248bfDhttp://resolver.tudelft.nl/uuid:85aa81cb4cf048c7a9fc95f6cef248bfeTransmission 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)We have developed a scheme that retrieves primary reflections in the twoway 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 twoway 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 multiplesenjournal articleEGreen Open Access added to TU Delft Institutional Repository You share, we take care! Taverne project https://www.openaccess.nl/en/yousharewetakecare 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.
20191026)uuid:e5a476136f6c48a6a81e16430c319586Dhttp://resolver.tudelft.nl/uuid:e5a476136f6c48a6a81e16430c319586=Electromagnetic Marchenko imaging in 1D for dissipative media3Zhang, 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)2Sicking, Charles (editor); Ferguson, John (editor)We present a onedimensional lossless scheme to compute an image of a dissipative medium from two singlesided 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<E a synthesized waveguide that could be used for measurements in a laboratory.Delectromagnetic; conductivity; internal multiples; permeability; GPRconference paperSEG#Applied Geophysics and Petrophysics)uuid:37a5a787e38849f59c22579dee5aa1efDhttp://resolver.tudelft.nl/uuid:37a5a787e38849f59c22579dee5aa1efQFrom closedboundary to singlesided 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)The homogeneous Green s function (i.e., the Green s function and its timereversed counterpart) plays an important role in optical, acoustic and seismic holography, in inverse scattering methods, in the field of timereversal acoustics, in reversetime migration and in seismic interferometry. Starting with the classical closedboundary representation of the homogeneous Green s function, we modify the configuration to two parallel boundaries. We discuss stepbystep a process that eliminates the integral along the lower boundary. This leads to a singlesided representation of the homogeneous Green s function. Apart from imaging, we foresee interesting applications in inverse scattering, timereversal acoustics, seismic interferometry, passive source imaging, etc.imaging; internal multiples)uuid:a3762abc0fae4b0bbea6aa571f2db3e2Dhttp://resolver.tudelft.nl/uuid:a3762abc0fae4b0bbea6aa571f2db3e2[Autofocusing imaging: Imaging with primaries, internal multiples and freesurface multiplesTSingh, S.; Snieder, R.; Behura, J.; van der Neut, J.R.; Wapenaar, C.P.A.; Slob, E.C.#Recent work on autofocusing with the Marchenko equation has shown how the Green's function for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green's function from the location of the virtual source to the surface. The Green's function is retrieved using only the reflection response of the medium and an estimate of the first arrival at the surface from the virtual source. Current techniques, however, only include primaries and internal multiples. Therefore, all surfacerelated multiples must be removed from the reflection response prior to Green's function retrieval. Here, we extend the Marchenko equation to retrieve the Green's function that includes primaries, internal multiples, and freesurface multiples. In other words, we retrieve the Green's function in the presence of a free surface. We use the associated Green's function for imaging the subsurface. The information needed for the retrieval are the reflection response at the surface and an estimate of the first arrival at the surface from the virtual source. The reflection response, in this case, includes the freesurface multiples; this makes it possible to include these multiples in the imaging operator and it obviates the need for surfacerelated multiple elimination.@imaging; multiples; scattering; autofocusing; internal multiples!Civil Engineering and GeosciencesGeoscience & Engineering
*+&ffffff?'ffffff?(?)?"dXX333333?333333?U}}}}}}}}}} }
}}}
}}}}}}}}}}}}
@
!
"
#
$
%
&@
'
(
)
*
+
,

.
/
&@
0
1
)
*
+
2
3
4
5x@
6
7
)
*
8
9
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\]^_`abcdefghijklmnopqrstuvwxyz{}~>@ddyKyKhttp://resolver.tudelft.nl/uuid:85aa81cb4cf048c7a9fc95f6cef248bfyKyKhttp://resolver.tudelft.nl/uuid:e5a476136f6c48a6a81e16430c319586yKyKhttp://resolver.tudelft.nl/uuid:37a5a787e38849f59c22579dee5aa1efyKyKhttp://resolver.tudelft.nl/uuid:a3762abc0fae4b0bbea6aa571f2db3e2gg
Root Entry FjaȄjaȄ@SummaryInformation( F<Workbook FDocumentSummaryInformation8 F
!"#$%&'()*+,./0123456789:;<=>?@ABCDEFGHIJKLM