"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"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: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:28ababd6-a8bb-46b8-8145-699d1b07106b","http://resolver.tudelft.nl/uuid:28ababd6-a8bb-46b8-8145-699d1b07106b","Imaging the earth's interior with virtual sources and receivers","Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics); van der Neut, J.R. (TU Delft Applied Geophysics and Petrophysics); Thorbecke, J.W. (TU Delft Applied Geophysics and Petrophysics); Slob, E.C. (TU Delft Applied Geophysics and Petrophysics); Snieder, R (Extern)","","2016","","","en","abstract","","","","","","","","","","","","","",""
"uuid:ea4c851a-94bd-40f3-b71d-885c1eaff00c","http://resolver.tudelft.nl/uuid:ea4c851a-94bd-40f3-b71d-885c1eaff00c","Imaging an unknown object in an unknown medium","Snieder, R (Colorado School of Mines); Wapenaar, C.P.A. (TU Delft Applied Geophysics and Petrophysics)","","2016","Imaging an unknown object in a medium that is known, such as a medium with constant velocity, is not difficult because one knows exactly where the waves are when they interact with the object. It is much more challenging to image an object in an unknown medium, because in that case one may know the waves that one sends into the medium, but one may does not know the waves that illuminate the object because the waves are distorted during their propagation to the object and back. Yet in many applications the medium is strongly scattering and the wavefield is strongly distorted as it propagates to the object. This is like imaging through frosted glass. How can one create an image in such media? And related to this, how can one focus a wavefield through a complicated medium that one does not know? Inverse scattering methods, as developed in quantum mechanics[1, 2], make it possible to estimate the model or object at a prescribed location without knowing the medium between that location and the point where reflected waves are recorded. These inverse scattering methods are known as the Marchenko equation or Gel’Fand-Levitan equation. Recently, these inverse scattering methods have been generalized to applications in seismology[3, 4, 5, 6] where one seeks to image a target, such as a reservoir, under a complicated overburden, such as a salt body. The main issue we will address is how it is possible that one can image the object at one location without knowing the medium between the observation point and the reconstruction point. The reason why inverse scattering make it possible to do this is that these methods involve an integral equation[7], and the function that one solves for is akin to the Green’s function for the unknown medium. The function obtained by solving the Marchenko equation is, in fact, the incident wavefield that will focus the waves at a specified target location. In order to solve this integral equation one only needs to know a smooth estimate of he velocity model and the reflected waves recorded at the acquisition surface, but the details of the complexity of the medium need not be known. That means there exists a recipe to determine, given the reflected waves, the incident wavefield that focuses at a specified target point. Such focusing is exactly what is needed to determine the image at the target point. There are many applications in geophysics where one seeks to create an image in strongly scattering media. These include hydrocarbon reservoirs under a complicated overburden, the interior of volcanoes, possibly the core mantle boundary, and crustal structure from high-frequency seismic waves.","imaging; inverse scattering","en","abstract","","","","","","","","","","","","","",""
"uuid:d70af4b3-b5b7-40e6-b1bc-0a7b08880bac","http://resolver.tudelft.nl/uuid:d70af4b3-b5b7-40e6-b1bc-0a7b08880bac","Seismic reflection imaging, accounting for primary and multiple reflections","Wapenaar, C.P.A.; Van der Neut, J.R.; Thorbecke, J.W.; Broggini, F.; Slob, E.C.; Snieder, R.","","2015","","","en","journal article","European Geosciences Union (EGU)","","","","","","","","Civil Engineering and Geosciences","Geoscience and Engineering","","","",""
"uuid:ef15255e-c92c-4615-bd63-b9525f7e25db","http://resolver.tudelft.nl/uuid:ef15255e-c92c-4615-bd63-b9525f7e25db","Marchenko imaging: Imaging with primaries, internal multiples, and free-surface multiples","Singh, S.; Snieder, R.; Behura, J.; van der Neut, J.R.; Wapenaar, C.P.A.; Slob, E.C.","","2015","Recent work on retrieving the Green’s function with the Marchenko equation shows how these functions for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green’s function from the location of the virtual source to the surface. The Green’s function is retrieved using only the reflection response of the medium and an estimate of the first arrival at the surface from the virtual source. Current techniques, however, only include primaries and internal multiples. Therefore, all surface-related multiples must be removed from the reflection response prior to Green’s function retrieval. We have extended the Marchenko equation to retrieve the Green’s function that includes primaries, internal multiples, and free-surface multiples. In other words, we have retrieved the Green’s function in the presence of a free surface. The information needed for the retrieval is the same as the current techniques, with the only difference being that the reflection response now also includes free-surface multiples. The inclusion of these multiples makes it possible to include them in the imaging operator, and it obviates the need for surface-related multiple elimination. This type of imaging with Green’s functions is called Marchenko imaging.","multiples; scattering; imaging; reflectivity; reciprocity","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:a3762abc-0fae-4b0b-bea6-aa571f2db3e2","http://resolver.tudelft.nl/uuid:a3762abc-0fae-4b0b-bea6-aa571f2db3e2","Autofocusing imaging: Imaging with primaries, internal multiples and free-surface multiples","Singh, S.; Snieder, R.; Behura, J.; van der Neut, J.R.; Wapenaar, C.P.A.; Slob, E.C.","","2014","Recent work on autofocusing with the Marchenko equation has shown how the Green's function for a virtual source in the subsurface can be obtained from reflection data. The response to the virtual source is the Green's function from the location of the virtual source to the surface. The Green's function is retrieved using only the reflection response of the medium and an estimate of the first arrival at the surface from the virtual source. Current techniques, however, only include primaries and internal multiples. Therefore, all surface-related multiples must be removed from the reflection response prior to Green's function retrieval. Here, we extend the Marchenko equation to retrieve the Green's function that includes primaries, internal multiples, and free-surface multiples. In other words, we retrieve the Green's function in the presence of a free surface. We use the associated Green's function for imaging the subsurface. The information needed for the retrieval are the reflection response at the surface and an estimate of the first arrival at the surface from the virtual source. The reflection response, in this case, includes the free-surface multiples; this makes it possible to include these multiples in the imaging operator and it obviates the need for surface-related multiple elimination.","imaging; multiples; scattering; autofocusing; internal multiples","en","conference paper","SEG","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:84266f03-b9e6-4fe6-9e74-a727c641d9f5","http://resolver.tudelft.nl/uuid:84266f03-b9e6-4fe6-9e74-a727c641d9f5","Marchenko imaging","Wapenaar, C.P.A.; Thorbecke, J.W.; Van der Neut, J.R.; Broggini, F.; Slob, E.C.; Snieder, R.","","2014","","","en","lecture notes","","","","","","","","","","","","","",""
"uuid:6b6317a1-9e4f-4d6b-bb2c-9e2d803e6625","http://resolver.tudelft.nl/uuid:6b6317a1-9e4f-4d6b-bb2c-9e2d803e6625","Autofocus imaging: Image reconstruction based on inverse scattering theory","Behura, J.; Wapenaar, C.P.A.; Snieder, R.","","2014","Conventional imaging algorithms assume single scattering and therefore cannot image multiply scattered waves correctly. The multiply scattered events in the data are imaged at incorrect locations resulting in spurious subsurface structures and erroneous interpretation. This drawback of current migration/imaging algorithms is especially problematic for regions where illumination is poor (e.g., subsalt), in which the spurious events can mask true structure. Here we discuss an imaging technique that not only images primaries but also internal multiples accurately. Using only surface reflection data and direct-arrivals, we generate the up- and down-going wavefields at every image point in the subsurface. An imaging condition is applied to these up- and downgoing wavefields directly to generate the image. Because the above algorithm is based on inverse-scattering theory, the reconstructed wavefields are accurate and contain multiply scattered energy in addition to the primary event. As corroborated by our synthetic examples, imaging of these multiply scattered energy helps eliminate spurious reflectors in the image. Other advantages of this imaging algorithm over existing imaging algorithms include more accurate amplitudes, target-oriented imaging, and a highly parallelizable algorithm.","","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:1f984a23-467a-499c-90a1-68e98b728ad8","http://resolver.tudelft.nl/uuid:1f984a23-467a-499c-90a1-68e98b728ad8","Data-driven wavefield focusing and imaging with multidimensional deconvolution: Numerical examples for reflection data with internal multiples","Broggini, F.; Snieder, R.; Wapenaar, C.P.A.","","2014","Standard imaging techniques rely on the single scattering assumption. This requires that the recorded data do not include internal multiples, i.e., waves that have bounced multiple times between reflectors before reaching the receivers at the acquisition surface. When multiple reflections are present in the data, standard imaging algorithms incorrectly image them as ghost reflectors. These artifacts can mislead interpreters in locating potential hydrocarbon reservoirs. Recently, we introduced a new approach for retrieving the Green’s function recorded at the acquisition surface due to a virtual source located at depth. We refer to this approach as data-driven wavefield focusing. Additionally, after applying source-receiver reciprocity, this approach allowed us to decompose the Green’s function at a virtual receiver at depth in its downgoing and upgoing components. These wavefields were then used to create a ghost-free image of the medium with either crosscorrelation or multidimensional deconvolution, presenting an advantage over standard prestack migration. We tested the robustness of our approach when an erroneous background velocity model is used to estimate the first-arriving waves, which are a required input for the data-driven wavefield focusing process. We tested the new method with a numerical example based on a modification of the Amoco model.","multiples; migration; reciprocity; crosscorrelation","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:61ad5e42-e10d-470c-a500-382090e1bff5","http://resolver.tudelft.nl/uuid:61ad5e42-e10d-470c-a500-382090e1bff5","Marchenko imaging","Wapenaar, C.P.A.; Thorbecke, J.W.; Van der Neut, J.R.; Broggini, F.; Slob, E.C.; Snieder, R.","","2014","Traditionally, the Marchenko equation forms a basis for 1D inverse scattering problems. A 3D extension of the Marchenko equation enables the retrieval of the Green’s response to a virtual source in the subsurface from reflection measurements at the earth’s surface. This constitutes an important step beyond seismic interferometry. Whereas seismic interferometry requires a receiver at the position of the virtual source, for the Marchenko scheme it suffices to have sources and receivers at the surface only. The underlying assumptions are that the medium is lossless and that an estimate of the direct arrivals of the Green’s function is available. The Green’s function retrieved with the 3D Marchenko scheme contains accurate internal multiples of the inhomogeneous subsurface. Using source-receiver reciprocity, the retrieved Green’s function can be interpreted as the response to sources at the surface, observed by a virtual receiver in the subsurface. By decomposing the 3D Marchenko equation, the response at the virtual receiver can be decomposed into a downgoing field and an upgoing field. By deconvolving the retrieved upgoing field with the downgoing field, a reflection response is obtained, with virtual sources and virtual receivers in the subsurface. This redatumed reflection response is free of spurious events related to internal multiples in the overburden. The redatumed reflection response forms the basis for obtaining an image of a target zone. An important feature is that spurious reflections in the target zone are suppressed, without the need to resolve first the reflection properties of the overburden.","multiples; migration; reciprocity","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:c9d6af44-5c03-4d03-b5b7-a9895cc37864","http://resolver.tudelft.nl/uuid:c9d6af44-5c03-4d03-b5b7-a9895cc37864","Green's function retrieval from reflection data, in absence of a receiver at the virtual source position","Wapenaar, C.P.A.; Thorbecke, J.W.; Van der Neut, J.R.; Broggini, F.; Slob, E.C.; Snieder, R.","","2014","The methodology of Green’s function retrieval by cross-correlation has led to many interesting applications for passive and controlled-source acoustic measurements. In all applications, a virtual source is created at the position of a receiver. Here a method is discussed for Green’s function retrieval from controlled-source reflection data, which circumvents the requirement of having an actual receiver at the position of the virtual source. The method requires, apart from the reflection data, an estimate of the direct arrival of the Green’s function. A single-sided three-dimensional (3D) Marchenko equation underlies the method. This equation relates the reflection response, measured at one side of the medium, to the scattering coda of a so-called focusing function. By iteratively solving the 3D Marchenko equation, this scattering coda is retrieved from the reflection response. Once the scattering coda has been resolved, the Green’s function (including all multiple scattering) can be constructed from the reflection response and the focusing function. The proposed methodology has interesting applications in acoustic imaging, properly accounting for internal multiple scattering.","","en","journal article","Acoustical Society of America","","","","","","","2014-11-01","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:33dea679-41a9-45b7-953f-987cdd26babd","http://resolver.tudelft.nl/uuid:33dea679-41a9-45b7-953f-987cdd26babd","Seismic reflector imaging using internal multiples with Marchenko-type equations","Slob, E.C.; Wapenaar, C.P.A.; Broggini, F.; Snieder, R.","","2014","We present an imaging method that creates a map of reflection coefficients in correct one-way time with no contamination from internal multiples using purely a filtering approach. The filter is computed from the measured reflection response and does not require a background model. We demonstrate that the filter is a focusing wavefield that focuses inside a layered medium and removes all internal multiples between the surface and the focus depth. The reflection response and the focusing wavefield can then be used for retrieving virtual vertical seismic profile data, thereby redatuming the source to the focus depth. Deconvolving the upgoing by the downgoing vertical seismic profile data redatums the receiver to the focus depth and gives the desired image. We then show that, for oblique angles of incidence in horizontally layered media, the image of the same quality as for 1D waves can be constructed. This step can be followed by a linear operation to determine velocity and density as a function of depth. Numerical simulations show the method can handle finite frequency bandwidth data and the effect of tunneling through thin layers.","imaging; reverse time migration; velocity analysis","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:f1750374-9a25-4f81-a5d5-e99279aec31e","http://resolver.tudelft.nl/uuid:f1750374-9a25-4f81-a5d5-e99279aec31e","Data-driven Green's function retrieval and application to imaging with multidimensional deconvolution","Broggini, F.; Wapenaar, C.P.A.; Van der Neut, J.R.; Snieder, R.","","2014","An iterative method is presented that allows one to retrieve the Green's function originating from a virtual source located inside a medium using reflection data measured only at the acquisition surface. In addition to the reflection response, an estimate of the travel times corresponding to the direct arrivals is required. However, no detailed information about the heterogeneities in the medium is needed. The iterative scheme generalizes the Marchenko equation for inverse scattering to the seismic reflection problem. To give insight in the mechanism of the iterative method, its steps for a simple layered medium are analyzed using physical arguments based on the stationary phase method. The retrieved Green's wavefield is shown to correctly contain the multiples due to the inhomogeneities present in the medium. Additionally, a variant of the iterative scheme enables decomposition of the retrieved wavefield into its downgoing and upgoing components. These wavefields then enable creation of a ghost-free image of the medium with either cross correlation or multidimensional deconvolution, presenting an advantage over standard prestack migration.","autofocusing; Marchenko; scattering; interferometry; Green's function","en","journal article","American Geophysical Union","","","","","","","2014-07-17","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:020d09ea-f839-4a5a-8e7f-2a18f151e92e","http://resolver.tudelft.nl/uuid:020d09ea-f839-4a5a-8e7f-2a18f151e92e","Interferometric redatuming of autofocused primaries and internal multiples","Van der Neut, J.; Slob, E.C.; Wapenaar, C.P.A.; Throbecke, J.W.; Snieder, R.; Broggini, F.","","2013","Recently, an iterative scheme has been introduced to retrieve the down- and upgoing Green's functions at an arbitrary level ?F inside an acoustic medium as if there were a source at the surface. This scheme requires as input the reflection response acquired at the surface and the direct arrival of the transmission response from the surface to level ?F. The source locations of these Green's functions can be effectively redatumed to level ?F by interferometric redatuming, which requires solving a multidimensional deconvolution problem, essentially being a Fredholm integral equation of the first kind. We show how this problem can be simplified by rewriting it as a Fredholm integral equation of the second kind that can be expanded as a Neumann series. Redatumed data can be used for multiplefree true-amplitude imaging at or in the vicinity of ?F. For imaging the closest reflector to ?F only, the Neumann series can be truncated at the first term without losing accuracy.","datuming; illumination; multiples; seismic","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:09ea03c7-f34c-4407-804d-a37531037f2a","http://resolver.tudelft.nl/uuid:09ea03c7-f34c-4407-804d-a37531037f2a","Data-driven Green's function retrieval and imaging with multidimensional deconvolution: Numerical examples for reflection data with internal multiples","Broggini, F.; Snieder, R.; Wapenaar, C.P.A.","","2013","Standard imaging techniques rely on the single scattering assumption. This requires that the recorded data do not include internal multiples, i.e. waves bouncing multiple times between layers before reaching the receivers at the acquisition surface. When multiple reflections are present in the data, standard imaging algorithms incorrectly image them as ghost reflectors. These artifacts can mislead the interpreters in locating potential hydrocarbon reservoirs. Recently, we introduced a new approach for retrieving the Greens function recorded at the acquisition surface due to a virtual source located at depth. Additionally, our approach allows us to decompose the Green's function in its downgoing and upgoing components. These wave fields are then used to create a ghostfree image of the medium with either crosscorrelation or multidimensional deconvolution, presenting an advantage over standard prestack migration. We illustrate the new method with a numerical example based on a modification of the Amoco model.","acoustic; migration; multiples","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:337306c1-4ad9-49a0-90de-bed90539994a","http://resolver.tudelft.nl/uuid:337306c1-4ad9-49a0-90de-bed90539994a","Three-dimensional Marchenko equation for Green's function retrieval “beyond seismic interferometry”","Wapenaar, C.P.A.; Slob, E.C.; Van der Neut, J.; Thorbecke, J.W.; Broggini, F.; Snieder, R.","","2013","In recent work we showed with heuristic arguments that the Green's response to a virtual source in the subsurface can be obtained from reflection data at the surface. This method is called “Green's function retrieval beyond seismic interferometry”, because, unlike in seismic interferometry, no receiver is needed at the position of the virtual source. Here we present a formal derivation of Green's function retrieval beyond seismic interferometry, based on a 3-D extension of the Marchenko equation. We illustrate the theory with a numerical example and indicate the potential applications in seismic imaging and AVA analysis.","multiples; reciprocity; wave equation; reverse-time","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:f9f4a019-9537-4040-b1d5-4c33a2093c18","http://resolver.tudelft.nl/uuid:f9f4a019-9537-4040-b1d5-4c33a2093c18","Data-driven green's function retrieval from reflection data: Theory and example","Wapenaar, C.P.A.; Slob, E.C.; Broggini, F.; Snieder, R.; Thorbecke, J.W.; Van der Neut, J.R.","","2013","Recently we introduced a new approach for retrieving the Green's response to a virtual source in the subsurface from reflection data at the surface. Unlike in seismic interferometry, no receiver is needed at the position of the virtual source. Here we present the theory behind this new method. First we introduce the Green's function G and a so-called fundamental solution F of an inhomogeneous medium. Next we derive a relation between G and F, using reciprocity theorems. This relation is used as the basis for deriving a 3D single-sided Marchenko equation. We show that this equation is solved by a 3D autofocusing scheme and that the Green's function is obtained by combining the focusing wave field and its response in a specific way. We illustrate the method with a numerical example.","","en","conference paper","Eage","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:f752f3d4-5f52-49e6-a309-5786f58dfae8","http://resolver.tudelft.nl/uuid:f752f3d4-5f52-49e6-a309-5786f58dfae8","3D Marine CSEM Interferometry by Multidimensional Deconvolution in the Wavenumber Domain for a Sparse Receiver Grid","Hunziker, J.W.; Slob, E.C.; Fan, Y.; Snieder, R.; Wapenaar, C.P.A.","","2013","We use interferometry by multidimensional deconvolution in combination with synthetic aperture sources in 3D to suppress the airwave and the direct field, and to decrease source uncertainty in marine Controlled-Source electromagnetics. We show with this numerical study that the method works for very large receiver spacing distances, even though the thereby retrieved reflection response may be aliased.","","en","conference paper","EAGE","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:b67674f6-c10f-4815-8a44-a746b9510521","http://resolver.tudelft.nl/uuid:b67674f6-c10f-4815-8a44-a746b9510521","Creating the green's response to a virtual source inside a medium using reflection data with internal multiples","Broggini, F.; Snieder, R.; Wapenaar, C.P.A.; Thorbecke, J.W.","","2013","Seismic interferometry is a technique that allows one to reconstruct the full wavefield originating from a virtual source inside a medium, assuming a receiver is present at the virtual source location. We discuss a method that creates a virtual source inside a medium from reflection data measured at the surface, without needing a receiver inside the medium and, hence, presenting an advantage over seismic interferometry. An estimate of the direct arriving wavefront is required in addition to the reflection data. However, no information about the medium is needed. We illustrate the method with numerical examples in a lossless acoustic medium with laterally-varying velocity and density. We examine the reconstructed wavefield when a macro model is used to estimate the direct arrivals and we take into consideration finite acquisition aperture. Additionally, a variant of the iterative scheme allows us to decompose the reconstructed wave field into downgoing and upgoing fields. These wave fields are then used to create an image of the medium with either crosscorrelation or multidimensional deconvolution.","","en","conference paper","EAGE","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:c6380fc3-f2f4-484c-ae6e-d11c499990c5","http://resolver.tudelft.nl/uuid:c6380fc3-f2f4-484c-ae6e-d11c499990c5","Electromagnetic interferometry in wavenumber and space domains in a layered earth","Hunziker, J.W.; Slob, E.C.; Fan, Y.; Snieder, R.; Wapenaar, C.P.A.","","2013","With interferometry applied to controlled-source electromagnetic data, the direct field and the airwave and all other effects related to the air-water interface can be suppressed in a data-driven way. Interferometry allows for retreival of the scattered field Green’s function of the subsurface or, in other words, the subsurface reflection response. This reflection response can then be further used to invert for the subsurface conductivity distribution. To perform interferometry in 3D, measurements on an areal grid are necessary. We discuss 3D interferometry by multidimensional deconvolution in the frequency-wavenumber and in the frequency-space domains and provide examples for a layered earth model. We use the synthetic aperture source concept to damp the signal at high wavenumbers to allow large receiver sampling distances. Interferometry indeed increases the detectability of a subsurface reservoir. Finally, we discuss the dependency of the accuracy of the retrieved reflection response on the two crucial parameters: the conductivity of the seabed at the receiver location and the stabilization parameter of the least-squares inversion.","electromagnetics; 3D; deconvolution; marine","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:9bccad08-b392-48a1-972e-fe68e4f7eba9","http://resolver.tudelft.nl/uuid:9bccad08-b392-48a1-972e-fe68e4f7eba9","Three-Dimensional Single-Sided Marchenko Inverse Scattering, Data-Driven Focusing, Green’s Function Retrieval, and their Mutual Relations","Wapenaar, C.P.A.; Broggini, F.; Slob, E.C.; Snieder, R.","","2013","The one-dimensional Marchenko equation forms the basis for inverse scattering problems in which the scattering object is accessible from one side only. Here we derive a three-dimensional (3D) Marchenko equation which relates the single-sided reflection response of a 3D inhomogeneous medium to a field inside the medium. We show that this equation is solved by a 3D iterative data-driven focusing method, which yields the 3D Green’s function with its virtual source inside the medium. The 3D single-sided Marchenko equation and its iterative solution method form the basis for imaging of 3D strongly scattering inhomogeneous media that are accessible from one side only.","","en","journal article","American Physical Society","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:fe7e739e-0f19-4a77-ba51-6273e92ba199","http://resolver.tudelft.nl/uuid:fe7e739e-0f19-4a77-ba51-6273e92ba199","Focusing the wavefield inside an unknown 1D medium: Beyond seismic interferometry","Broggini, F.; Snieder, R.; Wapenaar, C.P.A.","","2012","With seismic interferometry one can retrieve the response to a virtual source inside an unknown medium, if there is a receiver at the position of the virtual source. Using inverse scattering theory, we demonstrate that, for a 1D medium, the requirement of having an actual receiver inside the medium can be circumvented, going beyond seismic interferometry. In this case, the wavefield can be focused inside an unknown medium with independent variations in velocity and density using reflection data only.","","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:aa01d8e7-7782-48c1-8552-c97bbfdbee67","http://resolver.tudelft.nl/uuid:aa01d8e7-7782-48c1-8552-c97bbfdbee67","Synthesized 2D CSEM-interferometry Using Automatic Source Line Determination","Hunziker, J.W.; Slob, E.C.; Fan, Y.; Snieder, R.; Wapenaar, C.P.A.","","2012","Interferometry by multidimensional deconvolution applied to Controlled-Source Electromagnetic data replaces the medium above the receivers by a homogeneous halfspace, suppresses the direct field and redatums the source positions to the receiver locations. In that sense, the airwave and any other interactions of the signal with the air-water interface and the water layer are suppressed and the source uncertainty is reduced. Interferometry requires grid data and cannot be applied to line data unless the source is infinitely long in the crossline direction. To create such a source, a set of source lines is required. We use an iterative algorithm to determine the optimal locations of these source lines and show that more source lines are required if the source is towed closer to the sea bottom and closer to the receivers.","","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:569fa57f-bd3f-4e26-9c74-f544326125bd","http://resolver.tudelft.nl/uuid:569fa57f-bd3f-4e26-9c74-f544326125bd","Creating Virtual Sources Inside an Unknown Medium from Reflection Data: A New Approach to Internal Multiple Elimination","Wapenaar, C.P.A.; Thorbecke, J.W.; Van der Neut, J.R.; Broggini, F.; Snieder, R.","","2012","It has recently been shown that the response to a virtual source in the subsurface can be derived from reflection data at the surface and an estimate of the direct arrivals between the virtual source and the surface. Hence, unlike for seismic interferometry, no receivers are needed inside the medium. This new method recovers the complete wavefield of a virtual source, including all internal multiple scattering. Because no actual receivers are needed in the medium, the virtual source can be placed anywhere in the subsurface. With some additional processing steps (decomposition and multidimensional deconvolution) it is possible to obtain a redatumed reflection response at any depth level in the subsurface, from which all the overburden effects are eliminated. By applying standard migration between these depth levels, a true amplitude image of the subsurface can be obtained, free from ghosts due to internal multiples. The method is non-recursive and therefore does not suffer from error propagation. Moreover, the internal multiples are eliminated by deconvolution, hence no adaptive prediction and subtraction is required.","","en","conference paper","","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:a7510463-5446-4a49-a8fc-81f44db1d984","http://resolver.tudelft.nl/uuid:a7510463-5446-4a49-a8fc-81f44db1d984","Tutorial on seismic interferometry: Part 1 — Basic principles and applications","Wapenaar, C.P.A.; Draganov, D.S.; Snieder, R.; Campman, X.; Verdel, A.","","2010","Seismic interferometry involves the crosscorrelation of responses at different receivers to obtain the Green's function between these receivers. For the simple situation of an impulsive plane wave propagating along the x-axis, the crosscorrelation of the responses at two receivers along the x-axis gives the Green's function of the direct wave between these receivers. When the source function of the plane wave is a transient (as in exploration seismology) or a noise signal (as in passive seismology), then the crosscorrelation gives the Green's function, convolved with the autocorrelation of the source function. Direct-wave interferometry also holds for 2D and 3D situations, assuming the receivers are surrounded by a uniform distribution of sources. In this case, the main contributions to the retrieved direct wave between the receivers come from sources in Fresnel zones around stationary points. The main application of direct-wave interferometry is theretrieval of seismic surface-wave responses from ambient noise and the subsequent tomographic determination of the surface-wave velocity distribution of the subsurface. Seismic interferometry is not restricted to retrieving direct waves between receivers. In a classic paper, Claerbout shows that the autocorrelation of the transmission response of a layered medium gives the plane-wave reflection response of that medium. This is essentially 1D reflected-wave interferometry. Similarly, the crosscorrelation of the transmission responses, observed at two receivers, of an arbitrary inhomogeneous medium gives the 3D reflection response of that medium. One of the main applications of reflected-wave interferometry is retrieving the seismic reflection response from ambient noise and imaging of the reflectors in the subsurface. A common aspect of direct- and reflected-wave interferometry is that virtual sources are created at positions where there are only receivers without requiring knowledge of the subsurface medium parameters or of the positions of the actual sources.","geophysical techniques; Green's function methods; interferometry; seismic waves; seismology","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:07504f32-d9fb-46b9-8095-dcfa5b3e817b","http://resolver.tudelft.nl/uuid:07504f32-d9fb-46b9-8095-dcfa5b3e817b","Tutorial on seismic interferometry: Part 2 — Underlying theory and new advances","Wapenaar, C.P.A.; Slob, E.C.; Snieder, R.; Curtis, A.","","2010","In the 1990s, the method of time-reversed acoustics was developed. This method exploits the fact that the acoustic wave equation for a lossless medium is invariant for time reversal. When ultrasonic responses recorded by piezoelectric transducers are reversed in time and fed simultaneously as source signals to the transducers, they focus at the position of the original source, even when the medium is very complex. In seismic interferometry the time-reversed responses are not physically sent into the earth, but they are convolved with other measured responses. The effect is essentially the same: The time-reversed signals focus and create a virtual source which radiates waves into the medium that are subsequently recorded by receivers. A mathematical derivation, based on reciprocity theory, formalizes this principle: The crosscorrelation of responses at two receivers, integrated over differ-ent sources, gives the Green's function emitted by a virtual source at the position of one of the receivers and observed by the other receiver. This Green's function representation for seismic interferometry is based on the assumption that the medium is lossless and nonmoving. Recent developments, circumventing these assumptions, include interferometric representations for attenuating and/or moving media, as well as unified representations for waves and diffusion phenomena, bending waves, quantum mechanical scattering, potential fields, elastodynamic, electromagnetic, poroelastic, and electroseismic waves. Significant improvements in the quality of the retrieved Green's functions have been obtained with interferometry by deconvolution. A trace-by-trace deconvolution process compensates for complex source functions and the attenuation of the medium. Interferometry by multidimensional deconvolution also compensates for the effects of one-sided and/or irregular illumination.","deconvolution; geophysical techniques; Green's function methods; interferometry; seismic waves; seismology","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:9bf7fc0a-55ba-4cd0-91dd-b51b2064b638","http://resolver.tudelft.nl/uuid:9bf7fc0a-55ba-4cd0-91dd-b51b2064b638","On seismic interferometry, the generalized optical theorem, and the scattering matrix of a point scatterer","Wapenaar, C.P.A.; Slob, E.C.; Snieder, R.","","2010","We have analyzed the far-field approximation of the Green's function representation for seismic interferometry. By writing each of the Green's functions involved in the correlation process as a superposition of a direct wave and a scattered wave, the Green's function representation is rewritten as a superposition of four terms. When the scattered waves are modeled with the Born approximation, it appears that a three-term approximation of the Green's function representation (omitting the term containing the crosscorrelation of the scattered waves) yields a nearly exact retrieval, whereas the full four-term expression leads to a significant nonphysical event. This is because the Born approximation does not conserve energy and therefore is an insufficient model to explain all aspects of seismic interferometry. We use the full four-term expression of the Green's function representation to derive the generalized optical theorem. Unlike other recent derivations, which use stationary phase analysis, our derivation uses reciprocity theory. From the generalized optical theorem, we derive the nonlinear scattering matrix of a point scatterer. This nonlinear model accounts for primary and multiple scattering at the point scatterer and conforms with well-established scattering theory of classical waves. The model is essential to explain fully the results of seismic interferometry, even when it is applied to the response of a single point scatterer. The nonlinear scattering matrix also has implications for modeling, inversion, and migration.","geophysical techniques; Green's function methods; interferometry; seismic waves; seismology","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geoscience & Engineering","","","",""
"uuid:b8934b2b-1b8e-41dd-95a9-11deed023b0d","http://resolver.tudelft.nl/uuid:b8934b2b-1b8e-41dd-95a9-11deed023b0d","Unified Green's function retrieval by cross-correlation: Connection with energy principles","Snieder, R.; Wapenaar, K.; Wegler, U.","","2007","","","en","journal article","American Physical Society","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:5857194a-8e97-4b28-aaee-e77953dfc4bc","http://resolver.tudelft.nl/uuid:5857194a-8e97-4b28-aaee-e77953dfc4bc","Unified Green’s Function Retrieval by Cross Correlation","Wapenaar, C.P.A.; Slob, E.C.; Snieder, R.","","2006","It has been shown by many authors that the cross correlation of two recordings of a diffuse wave field at different receivers yields the Green’s function between these receivers. Recently the theory has been extended for situations where time-reversal invariance does not hold (e.g., in attenuating media) and where source-receiver reciprocity breaks down (in moving fluids). Here we present a unified theory for Green’s function retrieval that captures all these situations and, because of the unified form, readily extends to more complex situations, such as electrokinetic Green’s function retrieval in poroelastic or piezoelectric media. The unified theory has a wide range of applications in ‘‘remote sensing without a source.’’","","en","journal article","American Physical Society","","","","","","","","Civil Engineering and Geosciences","Geotechnology","","","",""
"uuid:bc099609-47bd-4ad8-91ad-2a4a9a949c0f","http://resolver.tudelft.nl/uuid:bc099609-47bd-4ad8-91ad-2a4a9a949c0f","Seismic interferometry-turning noise into signal","Curtis, A.; Gerstoft, P.; Sato, H.; Snieder, R.; Wapenaar, C.P.A.","","2006","Turning noise into useful data—every geophysicist's dream? And now it seems possible. The field of seismic interferometry has at its foundation a shift in the way we think about the parts of the signal that are currently filtered out of most analyses—complicated seismic codas (the multiply scattered parts of seismic waveforms) and background noise (whatever is recorded when no identifiable active source is emitting, and which is superimposed on all recorded data). Those parts of seismograms consist of waves that reflect and refract around exactly the same subsurface heterogeneities as waves excited by active sources. The key to the rapid emergence of this field of research is our new understanding of how to unravel that subsurface information from these relatively complex-looking waveforms. And the answer turned out to be rather simple. This article explains the operation of seismic interferometry and provides a few examples of its application.","geophysical techniques; seismology; structural engineering; earthquakes; interferometry","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","","","","",""
"uuid:c0512fe5-692e-47e3-98a2-a24cf29c0d09","http://resolver.tudelft.nl/uuid:c0512fe5-692e-47e3-98a2-a24cf29c0d09","Spurious multiples in seismic interferometry of primaries","Snieder, R.; Wapenaar, C.P.A.; Larner, K.","","2006","Seismic interferometry is a technique for estimating the Green's function that accounts for wave propagation between receivers by correlating the waves recorded at these receivers. We present a derivation of this principle based on the method of stationary phase. Although this derivation is intended to be educational, applicable to simple media only, it provides insight into the physical principle of seismic interferometry. In a homogeneous medium with one horizontal reflector and without a free surface, the correlation of the waves recorded at two receivers correctly gives both the direct wave and the singly reflected waves. When more reflectors are present, a product of the singly reflected waves occurs in the crosscorrelation that leads to spurious multiples when the waves are excited at the surface only. We give a heuristic argument that these spurious multiples disappear when sources below the reflectors are included. We also extend the derivation to a smoothly varying heterogeneous background medium.","interferometry; seismic waves; seismology","en","journal article","Society of Exploration Geophysicists","","","","","","","","Civil Engineering and Geosciences","Geotechnology","","","",""
"uuid:c3fd77aa-1a0f-4a71-92d2-86a722ed1366","http://resolver.tudelft.nl/uuid:c3fd77aa-1a0f-4a71-92d2-86a722ed1366","Retrieving the Green’s function in an open system by cross correlation: A comparison of approaches (L)","Wapenaar, C.P.A.; Fokkema, J.; Snieder, R.","","2005","We compare two approaches for deriving the fact that the Green’s function in an arbitrary inhomogeneous open system can be obtained by cross correlating recordings of the wave field at two positions. One approach is based on physical arguments, exploiting the principle of time-reversal invariance of the acoustic wave equation. The other approach is based on Rayleigh’s reciprocity theorem. Using a unified notation, we show that the result of the time-reversal approach can be obtained as an approximation of the result of the reciprocity approach.","Green's function methods; acoustic wave propagation; acoustic wave scattering; vibrations; structural acoustics; acoustic signal processing; seismology","en","journal article","Acoustical Society of America","","","","","","","","Civil Engineering and Geosciences","Geotechnology","","","",""