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1

Denoising of desert seismic signal based on synchrosqueezing transform and Adaboost algorithm

Sun Xiaofu, Li Yue

Acta Geophysica

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2020

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Vol. 68, no. 2

403--412

EN

Seismic data in desert area generally have low signal-to-noise ratio (SNR) due to special surface conditions. Desert noise is characterized as low-frequency, non-Gaussian and non-stationary noise, which makes the noise suppression in desert area more challenging by conventional methods. Conventional methods are efective for the signal with high SNR, but in desert seismic signal, the SNR is low and the signal can easily be obliterated in desert noise. In this paper, we propose an approach that operates in synchrosqueezing transform (SST) domain and use classifcation techniques obtained from supervised machine learning to identify the coefcients associated with signal and noise. First of all, we transform the real desert seismic data into time–frequency domain by SST. Secondly, we select features by calculating the SST coefcients of signal and noise. And then, we train them in the Adaboost classifer. Finally, when the training is completed, we can obtain the fnal classifer that can efectively separate the signal from noise. We perform tests on synthetic and feld records, and the results show great advantages in suppressing random noise as well as retaining efective signal amplitude.

2

Identification of seismic doublets occurred on Rudna mine, Poland

Rudziński Ł., Mirek J., Lizurek G.

Acta Geophysica

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2017

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Vol. 65, no. 2

287–-298

EN

Seismic events with similar focal mechanisms and similarity of Green‘s functions exhibit common waveform shapes recorded on the same seismic station. The similarity of seismograms can also be observed in the case of man-induced seismicity on the continuous excavated area. In this work, we focused on strong and potential mininginduced seismic doublets, our study was using concepts of signal analysis, using an in-mine network with quite low dynamic range. Since in such case records for strong events are usually affected by clipping, signal analysis were performed with both raw signal cross-correlation (CC) and binary signal cross-correlation (BCC). We found that for events which fulfilled the established criteria, waveform similarities are significantly higher than for other possible doublets. Using BCC and CC approaches, we noticed crucial influences of double couple nodal planes’ as well as P and T axis orientations on waveform similarities although the focal mechanisms were characterized by very high non-double couple components. Finally analysis confirmed that human activity represented by mining is able to produce strong (M[3) repeating mining tremors.

3

A study and application of high-resolution methods for reef reservoir identification

Yan L., Cheng B., Xu T., Wei S., Qian Z.

Acta Geophysica

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2017

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Vol. 65, no. 5

907--917

EN

Reefs represent a special type of carbonate trap that plays a key role in the migration, accumulation, and formation of a reservoir. They have commonly been the targets of exploration and development. However, reefs have complex interior structures and easily grow as thin, interbedded geological frames with reef microfacies that include the cap, core, and base of the reef. Because of the inherent drawbacks of seismic signals, including their low frequencies and narrow bandwidths, it is difficult to accurately identify reef reservoirs. Fortunately, the seismic frequency, phase, energy, waveform and other dynamic and geometrical properties can be used to compensate for the energy, expand the frequency bandwidth, and decompose and reconstruct the wavelet to obtain high-resolution seismic data. These data can highlight certain seismic responses of reefs, including boundary reflections, dome-shaped reflections from the reef outline, strong reflections from the reef cap, reflections from the reef bottom, and onlap reflections from the reef flanks. Some impedance response regularities, such as the lower impedance of the reef cap relative to the reef core and biodetritus beach and the fluctuating impedance of the reef-flat complex, are observed by combining log data with geological and high-resolution seismic data for a reef reservoir inversion. These methods were applied to the Changxing Formation in the Yuanba Gas Field. Good prediction results were obtained with a high consistency between the log and seismic data in a comparative analysis with the original seismic data and well logs.

4

Reef Reservoir Identification by Wavelet Decomposition and Reconstruction : A Case Study from Yuanba Gas Field in China

Cheng B., Xu T., Robbins B., Shen Z. M.

Acta Geophysica

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2015

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Vol. 63, no. 4

1025--1043

EN

The organic reef is a special type of carbonate reservoir which always dominates the spatial distribution, reserves and accumulations of natural gas. However, it is difficult to determine the organic reef’s internal structure and gas reservoirs due to numerous adverse factors such as the low resolution of seismic data, depth of burial, strong anisotropy, irregular spatial distribution and complex internal structure. A case study of wavelet decomposition and reconstruction technology applied to elucidate the features of organic reef reservoirs in the Changxing formation from Yuanba gas field shows that the seismic record reconstructed by high frequency signal can adequately describe the internal properties of organic reef reservoirs. Furthermore, the root mean square amplitude ratio of both low and high frequency data obtained from the reconstructed seismic data clearly show spatial distribution of gas and water in reef reservoirs.

5

Przetwarzanie danych sejsmicznych z wykorzystaniem nowej technologii przetwarzania, poprawiającej koherencję sygnału sejsmicznego

Masiukiewicz D., Lubomski S.

Prace Naukowe Instytutu Nafty i Gazu

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2012

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nr 182 wyd. konferencyjne

289--294

PL

Podstawowym celem przetwarzania danych sejsmicznych jest uzyskanie jak najwyższej jakości sekcji sejsmicznych. Zastosowanie standardowego schematu przetwarzania danych nie zawsze jest wystarczająco skuteczne, szczególnie w rejonach o niskim stosunku sygnału do zakłóceń. W Ośrodku Obliczeniowym Geofizyki Toruń wdrożono własną technologię poprawiającą koherencję sygnału ECP (Enhanced Coherency Processing) możliwą do zastosowania przed składaniem, po składaniu, dla 2D i 3D. W niniejszej pracy zaprezentowane zostały przykłady jej działania na danych sejsmicznych syntetycznych i rzeczywistych.

EN

The basic aim and goal of seismic data processing is to obtain the highest quality seismic section. Using a standard schema of data processing is not always sufficiently effective, especially in regions with low signal to noise ratio. In Seismic Data Processing Department of Geofzyka Toruń proprietary technology was implemented which improves the signal coherence ECP (Enhanced Coherency Processing). ECP can be used before stacking, as well as after stacking, for 2D and 3D. In this paper examples of obtained results of ECP were presented on synthetic and real seismic data.

6

Inwersja spektralna oparta na adaptacyjnej metodzie tworzenia rozwinięć sygnałów falkowych

Żuławiński K.

Nafta-Gaz

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2012

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R. 68, nr 12

937--948

PL

Przedstawiono metodę inwersji spektralnej sygnału sejsmicznego, przeprowadzono testy metody oraz zaprezentowano wyniki uzyskane dla wybranego profilu sejsmicznego. Omówiono podstawy matematyczne, począwszy od transformaty Gabora, jej porównanie z transformatą Fouriera oraz metodę słownikową rozwinięcia sygnału. W oparciu o te narzędzia zbudowano równanie macierzowe prowadzące do rozwiązania zadania odwrotnego przez stosowane w programowaniu liniowym metody optymalizacji, czyli dopasowanie adaptacyjne.

EN

The method of spectral inversion of seismic signals was presented and tested on theoretical and field data. The fundamental mathematical concepts, beginning with the Gabor transform, in comparison with the Fourier transform, and overcomplete signal representation based on dictionary of expansion functions were treated. On this ground a matrix equation was built and the method of its solution by linear programming field applied.

7

Modelling of a rock fall using the discrete element method and study of the seismic signal

Pater A., Dembicki E., Villard P.

Archives of Civil Engineering

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2008

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Vol. 54, nr 2

405-422

EN

The mechanism of big rock falls or avalanches is still poorly known, both for the rupture and propagation processes. The only quantitative data that are currently measured and available during a rock fall are the seismic signals recorded by seismological arrays. The signal properties (amplitude, duration, frequency) are obviously linked to the characteristics of the fall (mass, fall height, propagation distance) but no systematic study has been performed so far. This article aims at studying this relation by modeling the rock fall process. The used technique is the discrete element method (DEM) which allows to consider the different phenomena or parameters likely to influence the seismic signals: fracturing, rock fall type, morphology of the impact area.

PL

Mechanizm dużego spadającego bloku skalnego lub lawiny pozostaje nadal słabo rozpoznany zarówno w zakresie pęknięć jak i procesów propagacji. Jedynie ilościowe dane, które aktualnie są mierzone i uchwytne podczas spadania skały, zarejestrowane są jako sejsmiczne sygnały przez szereg sejsmografów. Właściwości sygnału (amplituda, trwanie, częstotliwość) są wyraźnie powiązane z cechami spadania (masa, wysokość spadania, odległość propagacji), lecz dotychczas nie były wykonane żadne systematyczne badania. Artykuł ma na celu badanie powyższej relacji za pomocą modelowania procesu spadającej skały. Do modelowania wykorzystano metodę elementów dyskretnych, która pozwala uwzględnić różne zjawiska bądź parametry mogące wpłynąć na sejsmiczny sygnał: pęknięcia, rodzaj spadającej skały, morfologię obszaru uderzenia.

8

Stabilność sygnału sejsmicznego w strefie bariery dolomitowej Ca2 na linii otworów Dzieduszyce-Templewo

Misiarz P.

Prace Instytutu Górnictwa Naftowego i Gazownictwa

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2000

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nr 110 wyd. konferencyjne

227--232

EN

The study was aimed at an interpretation of several seismic lines basing on the borehole data from distant wells. However, the seismic lines and the boreholes were located on the presumed barrier of the Main dolomite Ca2 of Zechstein. The basic assumption was firstly - a presence of similar facial style and stratigraphy at both locations and secondly a stability of the wavelet. Here, one line and one well exemplify the results. The analysis was carried out in the two regions represented on seismic lines: the main dolomite barriers zone and in the basinal part filled with thick interval of younger salt - Na2. The acceptable results of a wavelet extraction from seismic traces in the first region and the lack of such results for the second region proved the correctness of the above assumptions. Additionally, some remarks have been made regarding the pitfalls of stratigraphic modelling.