704 research outputs found
Marchenko inversion in one dimension
No full textOrientadores: Maria Amélia Novais Schleicher, Joerg Dietrich Wilhelm SchleicherDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica e Instituto de GeociênciasResumo: A função de Green focada em um ponto arbitrário pode ser obtida por meio da solução da equação integral de Marchenko ou das equações acopladas de Marchenko, utlizando-se métodos iterativos. A equação integral de Marchenko é uma equação integral unidimensional que relaciona a amplitude de espalhamento e o coeficiente de reflexão que deu origem ao campo espalhado, sendo assim, um problema de espalhamento inverso. As equações acopladas de Marchenko são oriundas da relação entre o dado s??smico (função de Green) e uma solução fundamental de um problema de propagação (equação de Helmholtz homogênea com perturbação na velocidade). Este trabalho de dissertação visa reunir as deduções teóricas da equação integral de Marchenko e das equações acopladas de Marchenko, bem como apresentar o resultado da implementação dos dois esquemas iterativos e a comparação entre eles. Além disso, propõe uma aplicação para detecção de camadas utilizando as funções de Green unidirecionais redatumadasAbstract: The Green¿s function focused at an arbitrary point can be obtained from the solution of the Marchenko integral equation or the coupled Marchenko equations, by means of iterative schemes. The Marchenko integral equation is an unidimensional integral equation that relates the scattering amplitude and the reflection coefficient that created the scattered field. Therefore this equation represents an inverse scattering problem. The coupled Marchenko equations are a result from the relationship between the seismic data (Green¿s function) and the fundamental solution of a propagation problem (homogeneous Helmholtz equation with velocity perturbation). In this master thesis, we unite and compare the theoretical derivations of the Marchenko integral equations and the coupled Marchenko equations and present the implementational results of two iterative schemes for solving them and their comparison. Moreover, we present an application of the scheme for the coupled equations for layer detection using the one-way redatumed Green¿s functionMestradoReservatórios e GestãoMestra em Ciências e Engenharia de Petróle
Marchenko without up/down decomposition on the Marmousi model and retrieval of the refracted waves: Are they caused by the Marchenko algorithm?
No full textMarchenko algorithms retrieve the Green’s function for arbitrary subsurface locations, and the retrieved Green’s function includes the primary and multiple reflected waves. The Marchenko algorithms require the estimate of the direct arrivals and the reflected waves; however, most previous Marchenko algorithms also require the up/down components of the Marchenko equation for the Green’s function retrieval. We use the Marmousi model to retrieve the Green’s function without using the up/-down components of the Marchenko equation and show that the retrieved Green’s function matches with the numerically modeled Green’s function. We also show that the refracted waves can be successfully produced independently from the acquisition geometry, i.e., singlesided or two-sided; however, the retrieval of refracted waves that arrive before the first primary waves is inconsistent with the requirement that the Green’s function vanishes before the direct wave. Even though we retrieve such refracted waves, they are caused by the injection of the direct wave into suciently detailed background velocity and density models instead of operations of the Marchenko algorithm on the recorded wavefields.Accepted Author ManuscriptApplied Geophysics and PetrophysicsImPhys/Medical Imagin
Gamasiphis angaridis Marchenko 2013
No full text196. Gamasiphis angaridis Marchenko, 2013 Gamasiphis angaridis Marchenko, 2013a: 382. Gamasiphis angaridis.— Marchenko, 2013b: 178. Type depository. Zoological Museum of Institute of Systematics and Ecology of Animals, Novosibirsk, Russia. Type locality and habitat. Kebezen village (51°55'N, 87°06'E), Turochak district, North-Eastern Altai, South Siberia, Russia, 22 June 2007, in litter in a forest with Pinus sylvestris [Pinaceae] — Abies sibirica [Pinaceae] — Betula pubescens [Betulaceae].Published as part of Castilho, Raphael C., Silva, Edmilson S., De, Gilberto J. & Halliday, Bruce, 2016, Catalogue of the family Ologamasidae Ryke (Acari: Mesostigmata), pp. 1-147 in Zootaxa 4197 (1) on page 58, DOI: 10.5281/zenodo.16844
Gamasiphis ochotensis Marchenko 2013
No full text245. Gamasiphis ochotensis Marchenko, 2013 Gamasiphis ochotensis Marchenko, 2013b: 173. Type depository. Zoological Museum, Institute of Systematics and Ecology of Animals, Novosibirsk, Russia. Type locality and habitat. Susunaiskii Ridge (47°00' N, 142°50' E), Sakhalin Island, Russia, 9 August 1990, litter in Betula ermanii [Betulaceae] and Abies sakhalinensis [Pinaceae]— Picea glehnii [Pinaceae] forest.Published as part of Castilho, Raphael C., Silva, Edmilson S., De, Gilberto J. & Halliday, Bruce, 2016, Catalogue of the family Ologamasidae Ryke (Acari: Mesostigmata), pp. 1-147 in Zootaxa 4197 (1) on page 66, DOI: 10.5281/zenodo.16844
Tackling Different Velocity Borne Challenges of the Elastodynamic Marchenko Method
No full textThe elastodynamic Marchenko method removes overburden interactions obscuring the target information. This method either relies on separability of the so-called focusing and Green's functions or requires an accurate initial estimate of the focusing and Green's function overlap. Hitherto, F1- and G-+ have been assumed separable, whereas F1+ and (G-)* share an unavoidable overlap, which has been considered understood but hard to predict without knowing the model. However, velocity differences between P- and S-waves cause so far unexplored fundamental challenges for elastodynamic Marchenko autofocusing. These challenges are analysed for horizontally-layered media. First, the F1-/G-+ separability assumption can be violated depending on the medium, the redatuming depth and the angle of incidence. Second, the initial estimate of the said unavoidable overlap can be even more complicated than originally thought, including some of the internal multiples. We propose a strategy where we trade-off this sophisticated initial estimate with a trivial one at the cost of a more restrictive F1-/G-+ separability assumption, or at the cost of introducing an overlap between F1- and G-+ instead. The proposed method finds the desired solutions convolved by an unknown matrix which we can hope to remove by exploiting energy conservation and minimum-phase properties of the focusing functions.Accepted author manuscriptApplied Geophysics and PetrophysicsQN/Theoretical PhysicsImPhys/Acoustical Wavefield Imagin
Adaptive double-focusing method for source-receiver Marchenko redatuming on field data
No full textWe 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.Applied Geophysics and PetrophysicsImPhys/Acoustical Wavefield Imagin
Towards understanding the impact of the evanescent elastodynamic mode coupling in Marchenko equation-based demultiple methods
No full textMarchenko equation-based methods promise data-driven, true-amplitude internal multiple elimination. The method is exact in 1-D acoustic media, however it needs to be expanded to account for the presence of 2- and 3-D elastodynamic wave-field phenomena, such as compressional (P) to shear (S) mode conversions, total reflections or evanescent waves. Mastering high waveform-fidelity methods such as this, could further advance amplitude vs offset analysis and lead to improved reservoir characterization. This method-expansion may comprise of re-evaluating the underlying assumptions and/or appending the scheme with additional constraints (e.g. minimum phase). To do that, one may need to better understand the construction of the Marchenko equation solutions, the so-called focusing functions, in a mathematically simple and numerically stable fashion. The latter could be a challenge at large angles of incidence where the elastodynamic effects and evanescent waves start playing a dominant role. We demonstrate that the elastodynamic focusing functions are the bridge between the Marchenko equation theory and the transfer matrix formalism. Using the latter, we show how we can try to gain further insights into how time-reversal (correlations) behaves when either of the elastic modes becomes evanescent. We also show how this construction allows us to shed light on into the mathematical properties of elastodynamic inverse transmissions, which takes us a step closer towards understanding the elastodynamic minimum phase reconstruction.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.Applied Geophysics and Petrophysic
Inverse scattering designs of dispersion-engineered single-mode planar waveguides
No full textWe use an inverse-scattering (IS) approach to design single-mode waveguides with controlled linear and higher-order dispersion. The technique is based on a numerical solution to the Gelfand-Levitan-Marchenko integral equation, for the inversion of rational reflection coefficients with arbitrarily large number of leaky poles. We show that common features of dispersion-engineered waveguides such as trenches, rings and oscillations in the refractive index profile come naturally from the IS algorithm without any a priori assumptions. Increasing the leaky-pole number increases the dispersion map granularity and allows design of waveguides with identical low order and differing higher order dispersion coefficients
Zerconopsini Makarova & Marchenko & Lindquist 2021, tribe n.
No full textZerconopsini tribe n. Type genus: Zerconopsis Hull, 1918. Diagnosis. Adult dorsal shield entire, often fully covering body dorsum, with or without lateral incisions, its setae mostly simple but usually some (1–8 pairs) paddle-shaped, rarely setae j 1, z 1 and often seta J 5 serrated or pilose. Sternal or sternitigenital shield consolidated with endopodal sclerites between coxae I–II and II–III but usually not connected with free endopodal strips between coxae III–IV. Female with ventrianal shield bearing 1–6 pairs of opisthogastric setae but never expansive enough to include metapodal platelets and setae JV 1; rarely, broad anal shield present bearing only three circumanal setae (Iphidonopsis). Peritreme long, its margins often crenulate. Subcapitulum with deutosternum wide or of moderate width; hypostomatic setae hp -1 and usually hp -3 elongated, often whip-like, 2–5 times longer than distance between them. Palp tarsus without distinct macroseta but apically with two distinct sensillae—large erect one with truncated tip, and curved “S”-like sensilla (Fig. 10). Palp trochanter internal seta whip-like, often much (3–6 times) longer than external seta (as an exception, 1.5 times in one undescribed Zerconopsis species). Male spermatodactyl of different length, tube-like, sometimes with membranous frenulum. Tarsus I with or without claws. Genu III usually plesiomorphically with eight setae (pv -1 present); tarsi II–IV each with dorso-proximal setae ad -2, pd -2 elongated, curved; males of few Zerconopsis species have ventral seta mv on tarsus II modified, thickened and attenuated. Genera included: Zerconopsis, Xenoseius, Iphidonopsis.Published as part of Makarova, Olga L., Marchenko, Irina I. & Lindquist, Evert E., 2021, Distribution, habitats, and redescription of the rare mite species Iphidonopsis sculptus Gwiazdowicz, 2004 (Mesostigmata: Ascidae), pp. 448-464 in Zootaxa 4952 (3) on page 450, DOI: 10.11646/zootaxa.4952.3.2, http://zenodo.org/record/469053
Application of the Marchenko method to a land seismic dataset
Get PDFThe Marchenko method is capable of estimating Green's functions between the
surface of the Earth and arbitrary locations in the subsurface. This method
enables the isolation of the response of a specific layer or package of layers,
free from the influence of the overburden and underburden. In this study, we
apply the Marchenko-based isolation technique to land S-wave seismic data
acquired in the Groningen province, the Netherlands, even though applying the
Marchenko method to land data is very challenging. We apply the technique for
three scenarios: overburden elimination, underburden elimination, and combined
elimination of the overburden and underburden. Our results indicate that this
approach partly enhances the resolution of reflections and eliminates internal
multiples. These enhanced reflections can be utilized for imaging and
monitoring applications, where we expect improved results due to the
elimination of the overburden and underburden.Comment: 10 pages, 7 figure
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