Kinematics of water‐bottom and diffracted 2D multiples in data space and image space

2005 ◽  
Author(s):  
Gabriel Alvarez
Keyword(s):  
Image Space ◽  
Data Space ◽  
Water Bottom

scholarly journals Attenuation of specular and diffracted 2D multiples in image space

Geophysics ◽  
2007 ◽  
Vol 72 (5) ◽  
pp. V97-V109 ◽  
Author(s):  
Gabriel Alvarez ◽  
Biondo Biondi ◽  
Antoine Guitton
Keyword(s):  
Radon Transform ◽  
3D Model ◽  
Model Space ◽  
Image Space ◽  
Attractive Alternative ◽  
Seismic Line ◽  
Data Space ◽  
Zero Curvature ◽  
Multiple Elimination ◽  
Water Bottom

In complex areas, the attenuation of specular and diffracted multiples in image space is an attractive alternative to surface-related multiple elimination (SRME) and to data space Radon filtering. We present the equations that map, via wave-equation migration, 2D diffracted and specular water-bottom multiples from data space to image space. We show the equations for both subsurface-offset-domain common-image-gathers (SODCIGs) and angle-domain common-image-gathers (ADCIGs). We demonstrate that when migrated with sediment velocities, the over-migrated multiples map to predictable regions in both SODCIGs and ADCIGs. Specular multiples focus similarly to primaries, whereas diffracted multiples do not. In particular, the apex of the residual moveout curve of diffracted multiples in ADCIGs is not located at the zero aperture angle. We use our equation of the residual moveout of the multiples in ADCIGs to design an apex-shifted Radon transform that maps the 2D ADCIGs into a 3D model space cube whose dimensions are depth, curvature, and apex-shift distance. Well-corrected primaries map to or near the zero-curvature plane and specularly reflected multiples map to or near the zero apex-shift plane. Diffracted multiples map elsewhere in the cube according to their curvature and apex-shift distance. Thus, specularly reflected as well as diffracted multiples can be attenuated simultaneously. We show the application of our apex-shifted Radon transform to a 2D seismic line from the Gulf of Mexico. Diffracted multiples originate at the edges of the salt body and we show that we can successfully attenuate them, along with the specular multiples, in the image Radon domain.

Multiple attenuation in the image space

Geophysics ◽  
2005 ◽  
Vol 70 (1) ◽  
pp. V10-V20 ◽  
Author(s):  
Paul Sava ◽  
Antoine Guitton
Keyword(s):  
Real Data ◽  
Velocity Model ◽  
Image Space ◽  
Radon Transforms ◽  
Data Space ◽  
Multiple Attenuation ◽  
3D Data ◽  
Propagation Effects ◽  
Wavefield Extrapolation ◽  
Multiple Elimination

Multiples can be suppressed in the angle-domain image space after migration. For a given velocity model, primaries and multiples have different angle-domain moveout and, therefore, can be separated using techniques similar to the ones employed in the data space prior to migration. We use Radon transforms in the image space to discriminate between primaries and multiples and employ accurate functions describing angle-domain moveouts. Since every individual angle-domain common-image gather incorporates complex 3D propagation effects, our method has the advantage of working with 3D data and complicated geology. Therefore, our method offers an alternative to the more expensive surface-related multiple-elimination (SRME) approach operating in the data space. Radon transforms are cheap but not necessarily ideal for separating primaries and multiples, particularly at small angles where the moveout discrepancy between the two kinds of events are not large. Better techniques involving signal/noise separation using prediction-error filters can be employed as well, although such approaches fall outside the scope of this paper. We demonstrate, using synthetic and real data examples, the power of our method in discriminating between primaries and multiples after migration by wavefield extrapolation, followed by transformation to the angle domain.

scholarly journals Interferometric redatuming by sparse inversion

2012 ◽  
Vol 192 (2) ◽  
pp. 666-670 ◽  
Author(s):  
Joost van der Neut ◽  
Felix J. Herrmann
Keyword(s):  
Least Squares ◽  
Image Space ◽  
Seismic Sources ◽  
Transform Domain ◽  
Frequency Content ◽  
Depth Level ◽  
Data Space ◽  
Sparse Inversion ◽  
Least Squares Migration ◽  
Incomplete Acquisition

Abstract Assuming that transmission responses are known between the surface and a particular depth level in the subsurface, seismic sources can be effectively mapped to this level by a process called interferometric redatuming. After redatuming, the obtained wavefields can be used for imaging below this particular depth level. Interferometric redatuming consists of two steps, namely (i) the decomposition of the observed wavefields into downgoing and upgoing constituents and (ii) a multidimensional deconvolution of the upgoing constituents with the downgoing constituents. While this method works in theory, sensitivity to noise and artefacts due to incomplete acquisition require a different formulation. In this letter, we demonstrate the benefits of formulating the two steps that undergird interferometric redatuming in terms of a transform-domain sparsity-promoting program. By exploiting compressibility of seismic wavefields in the curvelet domain, the method not only becomes robust with respect to noise but we are also able to remove certain artefacts while preserving the frequency content. Although we observe improvements when we promote sparsity in the redatumed data space, we expect better results when interferometric redatuming would be combined or integrated with least-squares migration with sparsity promotion in the image space.

scholarly journals Image-space surface-related multiple prediction

Geophysics ◽  
2007 ◽  
Vol 72 (2) ◽  
pp. S113-S122 ◽  
Author(s):  
Brad Artman ◽  
Gabriel Alvarez ◽  
Ken Matson
Keyword(s):  
Seismic Data ◽  
Velocity Model ◽  
Image Space ◽  
Depth Level ◽  
Image Domain ◽  
Data Space ◽  
The Earth ◽  
Multiple Prediction ◽  
The Cost ◽  
Multiple Elimination

A very important aspect of removing multiples from seismic data is accurate prediction of their kinematics. We cast the multiple prediction problem as an operation in the image space parallel to the conventional surface-related multiple-prediction methodology. Though developed in the image domain, the technique shares the data-driven strengths of data-domain surface-related multiple elimination (SRME) by being independent of the earth (velocity) model. Also, the data are used to predict the multiples exactly so that a Radon transform need not be designed to separate the two types of events. The cost of the prediction is approximately the same as that of data-space methods, though it can be computed during the course of migration. The additional cost is not significant compared to that incurred by shot-profile migration, though split-spread gathers must be used. Image-space multiple predictions are generated by autoconvolving the traces in each shot-gather at every depth level during the course of a shot-profile migration. The prediction in the image domain is equivalent to that produced by migrating the data-space convolutional prediction. Adaptive subtraction of the prediction from the image is required. Subtraction in the image domain, however, provides the advantages of focused energy in a smaller domain since extrapolation removes some of the imperfections of the input data.

High Resolution Specimen Area Imaged Under Negligible Field Aberrations

1970 ◽  
Vol 28 ◽  
pp. 540-541 ◽  
Author(s):  
T. Yanaka ◽  
K. Shirota
Keyword(s):  
High Resolution ◽  
Field Distribution ◽  
Image Space ◽  
Beam Deflection ◽  
Objective Lens ◽  
Resolution Limit ◽  
Leakage Flux ◽  
Specimen Area ◽  
Points Of View ◽  
Aberration Theory

It is significant to note field aberrations (chromatic field aberration, coma, astigmatism and blurring due to curvature of field, defined by Glaser's aberration theory relative to the Blenden Freien System) of the objective lens in connection with the following three points of view; field aberrations increase as the resolution of the axial point improves by increasing the lens excitation (k2) and decreasing the half width value (d) of the axial lens field distribution; when one or all of the imaging lenses have axial imperfections such as beam deflection in image space by the asymmetrical magnetic leakage flux, the apparent axial point has field aberrations which prevent the theoretical resolution limit from being obtained.

ANALYSIS OF ACCUMULATION AND DISTRIBUTION OF LEAD IN THE SYSTEM WATER-BOTTOM SEDIMENTS IN THE BACH DANG ESTUARY (VIETNAM)

2017 ◽  
pp. 62-66
Author(s):  
Truong Van Tuan ◽  
Irina Vladimirovna Volkova
Keyword(s):  
Bottom Sediment ◽  
Bottom Sediments ◽  
Water Samples ◽  
Suspended Solids ◽  
Natural Habitat ◽  
Bottom Layer ◽  
Sediment Samples ◽  
Natural Breeding ◽  
System Water ◽  
Water Bottom

Research was held in the estuary of the river Bach Dang (Dongbay community, Rakhtay district, Hai Phong, Vietnam) in June, 2012 - May, 2013. Concentration of lead was studied in water, suspended solids and bottom sediment. Clam beach (natural breeding environment of Meretrix lyrata ) was inspected regularly, every month. Water samples were taken 6 times from the bottom layer 10 cm down the bottom, once per 3 hours in each of 12 investigated zones. Bottom sediment samples were taken at the depth 2 cm. The findings show that lead accumulates mainly in suspended solids (23.3 mg/kg) and in bottom sediment (14.31 mg/kg), in water it is in small quantities (0.003 mg/kg). Analysis of bottom sediment samples taken in different places showed that they have even leadcontent, lead is distributed uniformly, localization of contaminations is not found. The results obtained can be assumed as the basis for investigating lead accumulation and its excretion by clam Meretrix lyrata organisms in the natural habitat.

INFLUENCE OF THE ECOLOGICAL STATE OF THE SEREPOK RIVER (VIETNAM) ON ACCUMULATION OF HEAVY METALS IN ORGANS OF FISH

2017 ◽  
pp. 98-105
Author(s):  
Ngo The Cuong ◽  
Tran Hoan Quoc ◽  
Svetlana Vasilievna Zolotokopova
Keyword(s):  
Heavy Metals ◽  
Heavy Metal ◽  
River Water ◽  
Bottom Sediments ◽  
Heavy Metal Concentration ◽  
Industrial Areas ◽  
Industrial Regions ◽  
Cadmium Lead ◽  
Sarotherodon Galilaeus ◽  
Water Bottom

The article focuses on the study of change of containing heavy metals (zinc, copper, iron, cadmium, lead, arsenic) in the abiotic and biotic components of the Serepok river (Vietman) influenced by wastewater discharge from industrial areas. Heavy metal content was determined in the river water and bottom sediments in the four zones: above and within the boundaries of industrial regions Xoa Phu and Tam Thang and in two water reservoirs situated below the boundaries of those industrial areas. Tilapia Galilean ( Sarotherodon galilaeus ), Hemibagrus ( Hemibagrus ), and sazan ( Cyprinus carpio ) caught in these areas were the hydrobionts under study in which liver, gills, skeleton and muscles accumulation of heavy metals was detected. In the organs of fish caught in the river within industrial region, heavy metals concentration was 3-7 times higher. The greatest concentration of heavy metals was found in the liver and gills of fish caught in the boundaries of industrial regions, the least concentration was in the muscles. In most cases, significant correlation between heavy metal concentration in organs of fishes and in river water, bottom sediments has been revealed.

Obraz, przestrzeń, rewolucja. Wszystkie sztuki okupacji

2013 ◽  
Author(s):  
W.J.T. Mitchell
Keyword(s):  
Image Space ◽  
Critical Inquiry ◽  
The Arts

Przekład tekstu "Image, Space, and Rewolution. The Arts of Occupation", który ukazał się w "Critical Inquiry" (2012, nr 39)

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