BazTech - Yadda

1

Verification of bright spots in the presence of thin beds by AVO and spectral analysis in Miocene sediments of Carpathian Foredeep

Cichostępski K., Kwietniak A., Dec J.

Acta Geophysica

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2019

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Vol. 67, no. 6

1731--1745

EN

Twin structural traps that lie within the Miocene strata of the Carpathian Foredeep that are localized above Cierpisz and Mrowla-Bratkowice highs exhibit identical bright-spot seismic anomalies, but only those associated with the Cierpisz high are profitable gas reservoirs. Bright spots can be a result of weak gas or water saturation, but also seismic interference known as tuning effect. For these reasons, it is crucial to differentiate between seismic anomalies. In this article, we present the possibilities of verification of seismic anomalies that occur within the siliciclastic Miocene sediments of the Carpathian Foredeep with the application of AVO analysis and spectral decomposition. AVO methodology enabled to limit the number of anomalies that are present in the post-stack seismic data. These anomalies, however, may also be a result of tuning which is common for the heterolithic sequences in the Miocene sediments of the Carpathian Foredeep. For classification of anomalies in the view of the above, spectral decomposition based on the Basis Pursuit algorithm was applied. Spectral decomposition enabled to divide AVO anomalies in those that are the result of gas saturation and the tuning effect. Gas-saturated zones are characterized by higher spectral amplitudes of the lower frequency range, whereas tuning effect yields higher spectral amplitudes for the higher frequency content. This relation is visible for the data set and enables qualitative differentiation for the set of seismic anomalies.

2

Fluid identification based on P-wave anisotropy dispersion gradient inversion for fractured reservoirs

Zhang J. W., Huang H. D., Zhu B. H., Liao W.

Acta Geophysica

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2017

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Vol. 65, no. 5

1081--1093

EN

Fluid identification in fractured reservoirs is a challenging issue and has drawn increasing attentions. As aligned fractures in subsurface formations can induce anisotropy, we must choose parameters independent with azimuths to characterize fractures and fluid effects such as anisotropy parameters for fractured reservoirs. Anisotropy is often frequency dependent due to wave-induced fluid flow between pores and fractures. This property is conducive for identifying fluid type using azimuthal seismic data in fractured reservoirs. Through the numerical simulation based on Chapman model, we choose the P-wave anisotropy parameter dispersion gradient (PADG) as the new fluid factor. PADG is dependent both on average fracture radius and fluid type but independent on azimuths. When the aligned fractures in the reservoir are meter-scaled, gas-bearing layer could be accurately identified using PADG attribute. The reflection coefficient formula for horizontal transverse isotropy media by Rüger is reformulated and simplified according to frequency and the target function for inverting PADG based on frequency-dependent amplitude versus azimuth is derived. A spectral decomposition method combining Orthogonal Matching Pursuit and Wigner–Ville distribution is used to prepare the frequency-division data. Through application to synthetic data and real seismic data, the results suggest that the method is useful for gas identification in reservoirs with meter-scaled fractures using high-qualified seismic data.

3

Spectral Decomposition Using the CEEMD Method: a Case Study from the Carpathian Foredeep

Kwietniak A., Cichostępski K., Kasperska M.

Acta Geophysica

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2016

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Vol. 64, no. 5

1525--1541

EN

The purpose of this work is to select the optimal spectral decomposition (SD) method for channel detection in the Miocene strata of the Carpathian Fordeep, SE Poland. For analysis, two spectral decomposition algorithms were tested on 3D seismic data: the first, based on Fast Fourier Transform (FFT), and second, on Complete Ensemble Empirical Mode Decomposition (CEEMD). Additionally the results of instantaneous frequency (IF) were compared with the results of peak frequency (PF) computed after the CEEMD. Both algorithms of SD enabled us to interpret channels, but the results are marginally different, i.e. the FFT shows more coarse, linear structures, that are desirable for channel interpretation, whereas the CEEMD does not highlight these structures as clearly and shows more, what the authors believe to be, noise.

4

Inwersja spektralna oraz dekompozycja spektralna w interpolacji cienkich warstw

Żuławiński K.

Prace Naukowe Instytutu Nafty i Gazu

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2012

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nr 182 wyd. konferencyjne

269--275

PL

Inwersję spektralną i dekompozycję spektralną łączy algorytm oparty na transformacji falkowej o zmiennej długości okna. Interpretacja sejsmiczna, wykorzystująca detekcję i śledzenie cienkich warstw oraz ich wyklinowań, zyskuje narzędzie obiektywnej oceny wyboru możliwych z punktu widzenia interpretatora wersji. Pokazane zostanie zastosowanie obu metod na przykładach modelowych i rzeczywistych.

EN

Both spectral inversion and spectral decomposition are joined by the algorithm of wavelet transform with variable size window. Seismic interpretation with use of detection and tracking of thin-beds and its edges gains universal tool for objective choice among various possible versions. The application of spectral inversion and decomposition for seismic models and real data will be shown.

5

Review on spectral decomposition of hookes tensor for all symmetry groups of linear elastic material

Kowalczyk-Gajewska K., Ostrowska-Maciejewska J.

Engineering Transactions

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2009

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Vol. 57, iss. 3/4

145-183

EN

The spectral decomposition of elasticity tensor for all symmetry groups of a linearly elastic material is reviewed. In the paper it has been derived in non-standard way by imposing the symmetry conditions upon the orthogonal projectors instead of the stiffness tensor itself. The numbers of independent Kelvin moduli and stiffness distributors are provided. The corresponding representation of the elasticity tensor is specified.

6

Zastosowanie dekompozycji spektralnej do oceny miąższości cienkich warstw

Tatarata A., Pietsch K., Marzec P.

Prace Instytutu Nafty i Gazu

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2006

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nr 137

207-212

PL

Dekompozycja spektralna pozwala na uzyskanie informacji o lokalnym spektrum częstotliwościowym danych sejsmicznych. Wykonane modelowania dowiodły, że wielkości amplitud poszczególnych komponentów spektralnych odpowiadają rzeczywistym miąższościom czasowym warstw. Podjęto próbę wykorzystania wniosków płynących z modelowań do danych rzeczywistych, zwracając uwagę na czynniki wpływające na interpretację.

EN

Spectral decomposition allows to derive the information about a local frequency spectrum of seismic data. Performed modelings proved that spectral components values respond to true time thicknesses of layers. Conclusions derived from the modelings were used in interpretation of the registered data. Factors having influence on interpretation were outlined.

7

Wykorzystanie metody dekompozycji spektralnej i klasyfikacji facji sejsmicznych w początkowym etapie interpretacji danych sejsmicznych 3D

Pomianowski P., Gierszewska D.

Prace Instytutu Nafty i Gazu

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2006

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nr 137

71-77

PL

Artykuł prezentuje wykorzystanie dekompozycji spektralnej (SD) i metody klasyfikacji facji sejsmicznych (WC) jako narzędzi do szybkiej identyfikacji perspektywicznych obiektów węglanowych o różnej genezie. Zaprezentowano i omówiono dwa przykłady zastosowania tych metod dla obiektów pochodzących z basenu permskiego w Polsce. Oba przykłady są związane z obiektami słabo widocznymi na standardowych sekcjach amplitudowych. Świadomie wybrano miejsca dobrze znane i wielokrotnie prezentowane, choć w innym aspekcie, w przeszłości. Intencją autorów było bowiem umożliwienie czytelnikom wyrobienie sobie własnej opinii na temat skuteczności i ewentualnych ograniczeń związanych ze stosowaniem obu metod. Obie metody zastosowano w strefie występowania obiektów u podnóża platform węglanowych Barnówko oraz Międzychód-Krobielewko. W niektórych miejscach stwierdzono później występowanie przemysłowego nagromadzenia węglowodorów. Porównanie obrazów uzyskanych w wyniku standardowej procedury interpretacyjnej połączonej z inwersją sejsmiczną z wynikami uzyskanymi w wyniku analizy spektralnej i klasyfikacji facji sejsmicznych wykazuje uderzające podobieństwo. Ta zgodność wyników potwierdza możliwość wykorzystania obu metod do uzyskiwania obrazu strukturalnego na początkowym etapie geologicznej interpretacji danych sejsmicznych. Dodatkowym atutem jest możliwość obrazowania obiektów, które ze względu na małą miąższość są trudne do identyfikacji na standardowych sekcjach amplitudowych.

EN

The paper shows an application of spectral decomposition and waveform classification as qualitative tools for fast delineation of different origin carbonate bodies. Two cases coming from Polish Permian Basin are presented and discussed here. Both of them are connected with objects hardly visible on amplitude seismic sections. All objects are well known what should help each of readers form his own opinion about the effectiveness of these methods. Spectral analysis was applied to slump bodies situated at the foot of carbonate platforms: Międzychód-Krobielewko and western most part of Barnówko-Mostno-Buszewo. In some places high porosity and hydrocarbon occurrence was later confirmed in such position. Comparison of final results of detailed amplitude interpretation and inversion modeling with pictures obtained from spectral analysis reveals striking similarity. It is clearly visible that working with discrete frequency images can expose a structural framework on a very initial stage of seismic data interpretation. Furthermore, these images not only confirmed the amplitude anomaly seen on the traditional amplitude map but also illuminated structures seemingly impossible to detect because of the tuning phenomenon. It also turned out that due to the different thickness of possible targets images prepared by digitally blended pictures of selected frequency show higher response to the geology than separate frequency slices.

8

Comparability groups

Foulis D., Foulis D.

Demonstratio Mathematica

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2006

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Vol. 39, nr 1

15-32

EN

A comparability group is a unital group with a compression base and with the general comparability property. The additive group of self-adjoint elements in a von Neumann algebra, and any Dedekind sigma-complete lattice-ordered abelian group with order unit are examples of comparability groups. We develop the basic theory of comparability groups, and show that an archimedean comparability group with the Rickart projection property can be embedded in a partially ordered rational vector space the elements of which admit a rational spectral resolution.

9

Improvement of spatial resolution of Brillouin optical time domain reflectometer using spectral decomposition

Zhang D., Shi B., Cui H.L., Xu H.Z.

Optica Applicata

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2004

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Vol. 34, nr 2

291-301

EN

Brillouin optical time domain reflectometer (BOTDR) has been used for strain and temperature measurement and health monitoring in infrastructural systems. However, the spatial measurement resolution of BOTDR cannot yet meet the measuring needs of some specific local strains, such as the strain caused by a narrow crack or fissure in structures. In this paper, a spectral decomposition method is proposed and used for improving the spatial resolution. Based on the proportion of the strain length within the spatial resolution, taking the spectrum of the strain section from the measured spectrum, and fitting the decomposed Brillouin gain spectrum with the Lorentzian curve, the actual strain within a spatial resolution along optical fibers can be obtained. The experimental results demonstrate that this method is applicable to the modification of the measured strain whether its strained length is less or greater than the spatial resolution without considering the installation method of the optical fiber