3D imaging challenges in steeply dipping mining structures: New lights on acquisition geometry and processing from the Brunswick no. 6 seismic data, Canada

Geophysics ◽  
2012 ◽  
Vol 77 (5) ◽  
pp. WC109-WC122 ◽  
Author(s):  
Saeid Cheraghi ◽  
Alireza Malehmir ◽  
Gilles Bellefleur
Keyword(s):  
Seismic Data ◽  
Mineral Exploration ◽  
High Amplitude ◽  
Special Focus ◽  
Seismic Profiles ◽  
Surface Reflection ◽  
Reflection Seismic ◽  
3D Data ◽  
Seismic Image ◽  
3D Information

We have analyzed and processed a [Formula: see text] nonorthogonal 3D surface reflection seismic data in the Brunswick no. 6 area to better understand the effect of acquisition geometry on the resultant image and to provide 3D information about the main geologic structures hosting the mineralization. The 3D data were processed using a conventional prestack dip moveout (DMO) and poststack migration algorithm with special focus on refraction static corrections, velocity analysis, and DMO corrections that are important for the data recorded in crystalline environment. However, the nonorthogonal nature of the 3D data combined with its narrow-azimuth, irregular offset distributions, and 2D nature of midpoint distribution in common depth point bins resulted in a lower quality seismic image than those observed on a series of 2D seismic profiles collected in the area prior to the 3D data acquisition. 2D wavenumber spectrum of the data suggests acquisition footprint associated with the data. Most of the noise associated with the acquisition footprint manifested itself as short-length, high-amplitude shallow reflections but largely were attenuated using a dip filter running in the wavenumber domain. Various bin size and geometries were tested, and the best result was obtained using rectangular bins aligned in the orientation of the shot lines. The processing results indicated that the highly prospective and mineralized Brunswick horizon is part of a continuous reflective package that could guide future deep mineral exploration in this mining camp.

Twelve years of vertical birefringence in nine‐component VSP data

Geophysics ◽  
2001 ◽  
Vol 66 (2) ◽  
pp. 582-597 ◽  
Author(s):  
Donald F. Winterstein ◽  
Gopa S. De ◽  
Mark A. Meadows
Keyword(s):  
Seismic Data ◽  
Azimuthal Anisotropy ◽  
Vertical Shear ◽  
S Wave ◽  
Seismic Profiles ◽  
Surface Reflection ◽  
Vertical Seismic Profiles ◽  
Reflection Seismic ◽  
San Andreas ◽  
Vsp Data

Since 1986, when industry scientists first publicly showed data supporting the presence of azimuthal anisotropy in sedimentary rock, we have studied vertical shear‐wave (S-wave) birefringence in 23 different wells in western North America. The data were from nine‐component vertical seismic profiles (VSPs) supplemented in recent years with data from wireline crossed‐dipole logs. This paper summarizes our results, including birefringence results in tabular form for 54 depth intervals in 19 of those 23 wells. In the Appendix we present our conclusions about how to record VSP data optimally for study of vertical birefringence. We arrived at four principal conclusions about vertical S-wave birefringence. First, birefringence was common but not universal. Second, birefringence ranged from 0–21%, but values larger than 4% occurred only in shallow formations (<1200 m) within 40 km of California’s San Andreas fault. Third, at large scales birefringence tended to be blocky. That is, both the birefringence magnitude and the S-wave polarization azimuth were often consistent over depth intervals of several tens to hundreds of meters but then changed abruptly, sometimes by large amounts. Birefringence in some instances diminished with depth and in others increased with depth, but in almost every case a layer near the surface was more birefringent than the layer immediately below it. Fourth, observed birefringence patterns generally do not encourage use of multicomponent surface reflection seismic data for finding fractured hydrocarbon reservoirs, but they do encourage use of crossed‐dipole logs to examine them. That is, most reservoirs were birefringent, but none we studied showed increased birefringence confined to the reservoir.

Cross-profile seismic data acquisition, imaging, and modeling of iron-oxide deposits: A case study from Blötberget, south-central Sweden

Geophysics ◽  
2020 ◽  
Vol 85 (6) ◽  
pp. B233-B247
Author(s):  
Georgiana Maries ◽  
Alireza Malehmir ◽  
Paul Marsden
Keyword(s):  
Iron Oxide ◽  
Seismic Data ◽  
Large Scale ◽  
Seismic Profiles ◽  
Data Set ◽  
Reflection Seismic ◽  
South Central ◽  
3D Data ◽  
Lateral Extent ◽  
3D Processing

Two 2D reflection seismic profiles were acquired in Blötberget, south-central Sweden, for deep targeting and delineation of sheet-like iron-oxide deposits, known to dip toward the southeast and extend down to at least 0.8 km depth from core drilling observations. The two perpendicular profiles recorded shots at every receiver station along the main and cross profiles. To obtain more information on the lateral extent of the mineralized horizons, data from the two profiles, including the cross-profile records, were binned together in a 3D grid and further processed as a 3D data set. Processing results suggest that more information is retrieved when 3D processing is used and the mineralization lateral extent can be inferred for at least 0.3 km. The seismic response of the mineralization was further studied through forward reflection traveltime modeling, using a 3D ray-tracing approach; thus, the 3D geometry of several planar reflectors was validated. Additionally, 2D elastic finite-difference modeling work showed that the observed reflection pattern in the seismic data may originate from several mineralized horizons, suggesting potential resources in the footwall of the known deposits and large-scale geologic structures. The results encourage the use of seismic methods for direct delineation of mineral deposits even from 2D profiles and prompted a 3D survey in the area.

A denoising framework for microseismic and reflection seismic data based on block matching

Geophysics ◽  
2018 ◽  
Vol 83 (5) ◽  
pp. V283-V292 ◽  
Author(s):  
Chao Zhang ◽  
Mirko van der Baan
Keyword(s):  
Seismic Data ◽  
Noise Suppression ◽  
Signal To Noise Ratio ◽  
Block Matching ◽  
The Novel ◽  
Noise Levels ◽  
Reflection Seismic ◽  
3D Data ◽  
2D Data ◽  
Incoherent Noise

Microseismic and seismic data with a low signal-to-noise ratio affect the accuracy and reliability of processing results and their subsequent interpretation. Thus, denoising is of great importance. We have developed an effective denoising framework for surface (micro)-seismic data using block matching. The novel idea of the proposed framework is to enhance coherent features by grouping similar 2D data blocks into 3D data arrays. The high similarities in the 3D data arrays benefit any filtering strategy suitable for multidimensional noise suppression. We test the performance of this framework on synthetic and field data with different noise levels. The results demonstrate that the block-matching-based framework achieves state-of-the-art denoising performance in terms of incoherent-noise attenuation and signal preservation.

scholarly journals Tertiary development of the Faeroe-Rockall Plateau based on reflection seismic data

1994 ◽  
Vol 41 ◽  
pp. 162-180
Author(s):  
L O. Baldreel ◽  
M.S. Andersen
Keyword(s):  
Seismic Data ◽  
Seismic Facies ◽  
Early Eocene ◽  
Ne Atlantic ◽  
Seismic Profiles ◽  
Norwegian Sea ◽  
Reflection Seismic ◽  
The North ◽  
Rockall Trough ◽  
Ne Atlantic Ocean

The Faeroe-Rockall Plateau is located in the NE Atlantic Ocean between Iceland and Scotland and is characterized by a late Paleocene-early Eocene basalt cover, which was extruded in association with the incipient opening of the NE Atlantic. The Faeroe-Rockall Plateau is separated from the NW European continental shelf by the Rockall Trough and the Faeroe­Shetland Channel, whose nature and age is still debated. Reflector configuration within the basalt allows volcanic seismic facies inteipretation to be carried out. The thickness of the basalt cover is estimated from reflection seismic data. Subbasalt geological structures are identified below subaerially extruded basalt on recently acquired as well as reprocessed seismic profiles. Overlying the basalt are early Eocene and younger Sediments. The distribution of these sedi- . ments is largely controlled by 1) the topography after the cessation of the volcanism, 2) the post volcanic subsidence of the area which is estimated from the depth to the breakpoints located on prim¥)' volcanic escaipments, 3) the Eocene-Miocene compressional tectonics which formed ridge& and minor basins, and 4) bottom currents of Norwegian Sea Deep Water (NSDW) which in the Neogene flowed into the North Atlantic south of the Greenland-Iceland-Faeroe-Scotland Ridg,e. A considerable part of the NSDW flows east and south of th

Comparison of geophone and surface-deployed distributed acoustic sensing seismic data

Geophysics ◽  
2019 ◽  
Vol 84 (2) ◽  
pp. A25-A29 ◽  
Author(s):  
Kyle T. Spikes ◽  
Nicola Tisato ◽  
Thomas E. Hess ◽  
John W. Holt
Keyword(s):  
Seismic Data ◽  
Fiber Optic ◽  
Single Strand ◽  
Near Surface ◽  
Acoustic Sensing ◽  
Surface Reflection ◽  
Reflection Seismic ◽  
Geophysical Surveys ◽  
Distributed Acoustic Sensing ◽  
High Level

The rapid and nonintrusive deployment of seismic sensors for near-surface geophysical surveys is of interest to make data acquisition efficient and to operate in a wide variety of environmental and surface-terrain conditions. We have developed and compared near-surface data acquired using a traditional vertical geophone array with data acquired using three different fiber optic cables operating in a distributed acoustic sensing (DAS) configuration. The DAS cables included a helically wrapped fiber, a nearly bare single-strand fiber, and an armored single-strand fiber. These three cables are draped on the ground alongside the geophones. Equivalent processing on colocated shot gathers resulted in a high level of similarity, in particular for reflection energy acquired through geophones and the helically wrapped cable. The single-strand fibers indicate much less similarity. Frequency content, however, differs in the raw and processed gathers from the geophones and the fiber optic cables. Nonetheless, results demonstrate that DAS technology can be used successfully to acquire near-surface reflection seismic data by deploying the cables on the surface. Potential applications for this technology include rapid deployment of active and/or passive arrays for near-surface geophysical characterization for various applications at different scales.

Joint inversion of seismic, vertical seismic profiling, and crosswell data — A case study from China

2017 ◽  
Vol 5 (1) ◽  
pp. T107-T119 ◽  
Author(s):  
Hemin Yuan ◽  
De-hua Han ◽  
Hui Li ◽  
Danping Cao
Keyword(s):  
Seismic Data ◽  
Joint Inversion ◽  
Seismic Inversion ◽  
Inversion Method ◽  
A Posteriori ◽  
Frequency Bandwidth ◽  
Surface Reflection ◽  
Seismic Profiling ◽  
Reflection Seismic ◽  
Vertical Seismic Profiling

Three-dimensional poststack and prestack seismic inversion results such as P- and S-impedance are commonly used for reservoir characterization. However, the frequency bandwidth of surface-based reflection seismic surveys usually ranges from 10 to 70 Hz, and these surveys have limited vertical resolution. The frequency bandwidth of vertical seismic profiling (VSP) and crosswell data is much wider than that of surface reflection seismic data, and it can give a detailed illumination of the subsurface around the borehole. We test a joint inversion method that integrated surface reflection seismic, VSP, and crosswell data. To better constrain the inversion results, we further integrate a posteriori information on the reflectivity obtained from petrophysics data into the inversion procedure. The a posteriori distribution we use is a modified-Cauchy distribution obtained from the statistical analysis of petrophysics data. To demonstrate the effectiveness of our algorithm, we applied our inversion strategy to a 2D synthetic model and a real seismic data set, and an uncertainty assessment was also performed. The joint inversion method can detect the thin layers that surface seismic inversion fail to, demonstrating the higher resolution of the method.

Uncertainty in determining interval velocities from surface reflection seismic data

Geophysics ◽  
2002 ◽  
Vol 67 (3) ◽  
pp. 952-963 ◽  
Author(s):  
Dan D. Kosloff ◽  
Yonadav Sudman
Keyword(s):  
Layer Thickness ◽  
Seismic Data ◽  
Single Layer ◽  
Seismic Survey ◽  
Fourier Domain ◽  
Layer Depth ◽  
Surface Reflection ◽  
Reflection Seismic ◽  
Spurious Oscillations ◽  
Interval Velocities

The ability of reflection seismic data to uniquely determine the subsurface velocity has been uncertain. This paper uses a tomographic approach to study the resolution of typical seismic survey configurations. The analysis is first carried out in the spatial Fourier domain for the case of a single horizontal reflector. It is found that for a ratio of maximum offset to layer depth of one, the lateral resolution is very low for velocity and interface depth variations of wavelengths of approximately two‐and‐a‐half times the layer thickness. The resolution improves with an increase in the ratio of maximum offset to layer depth. The results of the analysis in the Fourier domain are confirmed by results from a least‐squares tomographic algorithm. It is found that regularization of the tomography by adding damping terms suppresses the spurious oscillations resulting from the areas of low resolution at the expense of loss of resolution at the shorter spatial wavelengths. Analysis of the single layer response for 3‐D survey geometry shows that a 3‐D acquisition with multiazimuthal coverage has the potential to significantly improve velocity determination.

APPLICATION OF THE EMPIRICAL MODE DECOMPOSITION METHOD TO GROUND-ROLL NOISE ATTENUATION IN SEISMIC DATA

2013 ◽  
Vol 31 (4) ◽  
pp. 619 ◽  
Author(s):  
Luiz Eduardo Soares Ferreira ◽  
Milton José Porsani ◽  
Michelângelo G. Da Silva ◽  
Giovani Lopes Vasconcelos
Keyword(s):  
Empirical Mode Decomposition ◽  
Seismic Data ◽  
Low Frequency ◽  
High Amplitude ◽  
Seismic Line ◽  
Seismic Processing ◽  
Mode Decomposition ◽  
Ground Roll ◽  
Fortran 90 ◽  
Emd Method

ABSTRACT. Seismic processing aims to provide an adequate image of the subsurface geology. During seismic processing, the filtering of signals considered noise is of utmost importance. Among these signals is the surface rolling noise, better known as ground-roll. Ground-roll occurs mainly in land seismic data, masking reflections, and this roll has the following main features: high amplitude, low frequency and low speed. The attenuation of this noise is generally performed through so-called conventional methods using 1-D or 2-D frequency filters in the fk domain. This study uses the empirical mode decomposition (EMD) method for ground-roll attenuation. The EMD method was implemented in the programming language FORTRAN 90 and applied in the time and frequency domains. The application of this method to the processing of land seismic line 204-RL-247 in Tacutu Basin resulted in stacked seismic sections that were of similar or sometimes better quality compared with those obtained using the fk and high-pass filtering methods.Keywords: seismic processing, empirical mode decomposition, seismic data filtering, ground-roll. RESUMO. O processamento sísmico tem como principal objetivo fornecer uma imagem adequada da geologia da subsuperfície. Nas etapas do processamento sísmico a filtragem de sinais considerados como ruídos é de fundamental importância. Dentre esses ruídos encontramos o ruído de rolamento superficial, mais conhecido como ground-roll . O ground-roll ocorre principalmente em dados sísmicos terrestres, mascarando as reflexões e possui como principais características: alta amplitude, baixa frequência e baixa velocidade. A atenuação desse ruído é geralmente realizada através de métodos de filtragem ditos convencionais, que utilizam filtros de frequência 1D ou filtro 2D no domínio fk. Este trabalho utiliza o método de Decomposição em Modos Empíricos (DME) para a atenuação do ground-roll. O método DME foi implementado em linguagem de programação FORTRAN 90, e foi aplicado no domínio do tempo e da frequência. Sua aplicação no processamento da linha sísmica terrestre 204-RL-247 da Bacia do Tacutu gerou como resultados, seções sísmicas empilhadas de qualidade semelhante e por vezes melhor, quando comparadas as obtidas com os métodos de filtragem fk e passa-alta.Palavras-chave: processamento sísmico, decomposição em modos empíricos, filtragem dados sísmicos, atenuação do ground-roll.

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