VELOCITY AND FREQUENCY FILTERING OF SEISMIC DATA USING LASER LIGHT

Geophysics ◽  
1965 ◽  
Vol 30 (6) ◽  
pp. 1144-1178 ◽  
Author(s):  
Milton B. Dobrin ◽  
Arthur L. Ingalls ◽  
James A. Long
Keyword(s):  
Diffraction Pattern ◽  
Seismic Data ◽  
Optical Resolution ◽  
Processing System ◽  
Variable Density ◽  
Multiple Reflections ◽  
Optical Processing ◽  
Structural Problems ◽  
Optical Grating ◽  
Low Pass

When coherent light from a laser beam is passed through a transparent reduction of a variable‐density or variable‐area record section, the seismic signals act as an optical grating to produce a diffraction pattern which is the two‐dimensional Fourier transform of the section itself. With suitable lenses the diffraction pattern can be converted back into an image of the original section. By obstructing portions of the pattern corresponding to particular frequencies or dips on the section one can remove such frequencies or dips from the reconstructed image. The equipment developed for this processing incorporates special design features to combine high optical resolution, precise discrimination of moveouts and frequencies, limitation in the length of the overall optical path to permit the use of a short optical bench, and visual monitoring by use of a microscope or a closed‐circuit TV system. Filter elements consist of wedges mounted on a rotary stand for velocity rejection, wires of various diameters for band stop frequency rejection, and plates bounded by knife edges for low‐pass filtering. The technique is applicable to most problems encountered in seismic prospecting where spurious events obscure desired reflections. The most frequent application so far has been the removal of multiple reflections. The method has turned out to be highly useful for eliminating noise, regardless of origin, which interferes with reflections whenever the noise consists of traveling events, even though fragmental, which have different apparent velocities from the reflections. The method has also been effective in solving structural problems in tectonic areas by removing diffractions or, alternatively, by enhancing them at the expense of the reflections to delineate faults and other sources of diffraction. Ringing or reverberation can often be attenuated or eliminated in marine shooting by passing reflection frequencies that are less than the lowest observed harmonic of the fundamental reverberation frequency. Examples are shown of transforms and/or filtered sections illustrating these applications. A particularly valuable feature of this optical processing system is the ease of monitoring the results. The facility with which this can be done gives the technique distinct advantages over digital or analog methods, where the geophysicist loses contact with his results while processing is under way. Optical filtering also offers an intrinsically more economical approach to seismic data processing because hundreds of information channels can be handled n a single photographic operation.

OPTICAL PROCESSING AND INTERPRETATION

Geophysics ◽  
1967 ◽  
Vol 32 (5) ◽  
pp. 801-818 ◽  
Author(s):  
John C. Fitton ◽  
Milton B. Dobrin
Keyword(s):  
Seismic Data ◽  
Optical Filters ◽  
Frequency Discrimination ◽  
Visual Presentation ◽  
Processing Technique ◽  
Multiple Reflections ◽  
Optical Processing ◽  
Seismic Section ◽  
Optical Techniques ◽  
One Dimensional

Although the use of optical techniques for enhancing seismic data has become well established, the applicability of these techniques to seismic interpretation is not so widely recognized. Optical processing is ideally suited for use as a direct aid to interpretation because of the precision with which filtering can be controlled and because of the flexibility made possible by the instantaneous visual presentation of the filtered data. Frequency relationships in seismic data have great value in interpretation, and optical techniques are particularly suitable for bringing out such relationships. The one‐dimensional optical transform displays a channel‐by‐channel spectrum of a seismic section from which useful geological information can be inferred. On such transforms significant effects can often be brought out which are not discernible on the corresponding record sections. Reefs, for example, often cause a thinning of overlying formations which gives rise to a high‐frequency anomaly on the transform, even at levels so shallow in the section that no evidence for reef effects is apparent to the eye on the original records. Characteristic frequency anomalies can also be observed over faults. One‐dimensional transforms from sections made over features of both kinds show diagnostic patterns that can be used as a basis for detection. The sharp cutoffs and flexibility available in optical filters make it possible to discriminate between conflicting events on record sections by frequency filtering alone. With proper monitoring, one can select those cutoff frequencies which bring out events that appear geologically most plausible. Multiple reflections, for example, can often be eliminated by frequency discrimination once the geophysicist identifies the primary reflections on the monitor. Often seismic records are discarded as useless, when in reality they are simply too complex to interpret because a large number of events, all potentially significant, overlap. Such events can be sorted out for possible use by optical filtering and concurrent monitoring. No other processing technique allows the geophysicist to do this so easily.

LONG-PERIOD SURFACE-RELATED MULTIPLE SUPPRESSION IN 2D MARINE SEISMIC DATA USING PREDICTIVE DECONVOLUTION AND COMBINATION OF SURFACE-RELATED MULTIPLE ELIMINATION AND PARABOLIC RADON FILTERING

2021 ◽  
Author(s):  
Pimpawee Sittipan ◽  
Pisanu Wongpornchai
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Petroleum Reservoirs ◽  
The United States ◽  
Multiple Reflections ◽  
Long Period ◽  
Predictive Deconvolution ◽  
Short Period ◽  
Marine Seismic ◽  
Multiple Elimination

Some of the important petroleum reservoirs accumulate beneath the seas and oceans. Marine seismic reflection method is the most efficient method and is widely used in the petroleum industry to map and interpret the potential of petroleum reservoirs. Multiple reflections are a particular problem in marine seismic reflection investigation, as they often obscure the target reflectors in seismic profiles. Multiple reflections can be categorized by considering the shallowest interface on which the bounces take place into two types: internal multiples and surface-related multiples. Besides, the multiples can be categorized on the interfaces where the bounces take place, a difference between long-period and short-period multiples can be considered. The long-period surface-related multiples on 2D marine seismic data of the East Coast of the United States-Southern Atlantic Margin were focused on this research. The seismic profile demonstrates the effectiveness of the results from predictive deconvolution and the combination of surface-related multiple eliminations (SRME) and parabolic Radon filtering. First, predictive deconvolution applied on conventional processing is the method of multiple suppression. The other, SRME is a model-based and data-driven surface-related multiple elimination method which does not need any assumptions. And the last, parabolic Radon filtering is a moveout-based method for residual multiple reflections based on velocity discrimination between primary and multiple reflections, thus velocity model and normal-moveout correction are required for this method. The predictive deconvolution is ineffective for long-period surface-related multiple removals. However, the combination of SRME and parabolic Radon filtering can attenuate almost long-period surface-related multiple reflections and provide a high-quality seismic images of marine seismic data.

Pseudo-Color Coded Optical System Based on the Spatial Light Modulator and Charge-Coupled Device

2012 ◽  
Author(s):  
S. N. Zhao ◽  
H. Chang ◽  
J. Wei ◽  
Z. Wei
Keyword(s):  
Real Time ◽  
Optical System ◽  
Spatial Light Modulator ◽  
Processing System ◽  
Optical Processing ◽  
Gray Scale ◽  
Light Modulator ◽  
Time Modulation ◽  
Gray Scale Image ◽  
Pseudo Color

A new pseudo-color coded optical system based on the liquid crystal spatial light modulator (LC-SLM) and a digital camera (CCD) is proposed. The SLM is used to replace the holographic grating with gray-scale image information, a gray-scale image in real-time modulation methods is proposed by synthesizing phase hologram and Ronchi grating, combined with the 4f coherent optical processing system and spatial filtering. For the high resolution gray image processed with existing digital pseudo-color method, the color sensitivity is low, algorithm is very complex. For traditional optical pseudo-color method, the gray scale image needs chemical pretreatment. The process is complex and time-consuming, and the real-time modulation could not be achieved. Our new method has enhanced the flexibility and adaptability of the optical pseudo-color, and give full play to the high sensitivity, high-capacity, rich colors and other features of the optical processing mode. At the same time, it overcomes the disadvantages of pure optical system which could not perform real-time processing. Therefore, it can be widely used in the field of remote sensing, biomedical, environmental monitoring, public security and criminal investigation, etc.

2.5-D wave equations and high‐frequency asymptotics

Geophysics ◽  
1995 ◽  
Vol 60 (2) ◽  
pp. 556-562 ◽  
Author(s):  
John W. Stockwell
Keyword(s):  
Seismic Data ◽  
High Frequency ◽  
Wave Equations ◽  
Maximum Amplitude ◽  
Variable Density ◽  
Constant Density ◽  
Correction Factors ◽  
Wave Operators ◽  
Ray Series ◽  
D Wave

The need for modeling 3-D seismic data in a 2-D setting has motivated investigators to create so‐called 2.5-D modeling methods. One such method proposed by Liner involves the use of an approximate 2.5-D wave operator for constant‐density media. The traveltimes and amplitudes predicted by high‐frequency asymptotic ray series (WKBJ) analysis of the Liner 2.5-D wave equation match those predicted by Bleistein’s 2.5-D ray‐theoretic development in constant wavespeed media. However, high‐frequency analysis indicates that the Liner 2.5-D variable wavespeed equation will have a maximum amplitude error of ±35% in a linear c(z) model where the wavespeed doubles or halves from the beginning to the end of a raypath. These amplitudes are comparable to those produced by converting 2-D data to 2.5-D using correction factors of the type proposed by Emersoy and Oristaglio and Deregowski and Brown, with the exception being that the Liner equation lacks the half derivative waveform correction present in these operators. An alternate method of constructing 2.5-D wave operators based on the WKBJ analysis is proposed. This method permits variable density (acoustic) 2.5-D wave operators to be derived.

Deep‐water peg legs and multiples: Emulation and suppression

Geophysics ◽  
1986 ◽  
Vol 51 (12) ◽  
pp. 2177-2184 ◽  
Author(s):  
J. R. Berryhill ◽  
Y. C. Kim
Keyword(s):  
Wave Equation ◽  
Seismic Data ◽  
Water Layer ◽  
Original Data ◽  
Equation Method ◽  
Multiple Reflections ◽  
Step Method ◽  
Arrival Times ◽  
Sea Floor ◽  
Water Bottom

This paper discusses a two‐step method for predicting and attenuating multiple and peg‐leg reflections in unstacked seismic data. In the first step, an (observed) seismic record is extrapolated through a round‐trip traversal of the water layer, thus creating an accurate prediction of all possible multiples. In the second step, the record containing the predicted multiples is compared with and subtracted from the original. The wave‐equation method employed to predict the multiples takes accurate account of sea‐floor topography and so requires a precise water‐bottom profile as part of the input. Information about the subsurface below the sea floor is not required. The arrival times of multiple reflections are reproduced precisely, although the amplitudes are not accurate, and the sea floor is treated as a perfect reflector. The comparison step detects the similarities between the computed multiples and the original data, and estimates a transfer function to equalize the amplitudes and account for any change in waveform caused by the sea‐floor reflector. This two‐step wave‐equation method is effective even for dipping sea floors and dipping subsurface reflectors. It does not depend upon any assumed periodicity in the data or upon any difference in stacking velocity between primaries and multiples. Thus it is complementary to the less specialized methods of multiple suppression.

Multitarget-tracking optical processing system

1994 ◽  
Vol 33 (29) ◽  
pp. 6860
Author(s):  
David Casasent ◽  
Mark Yee
Keyword(s):  
Processing System ◽  
Multitarget Tracking ◽  
Optical Processing

Amplitude preservation of Radon-based multiple-removal filters

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. V123-V126 ◽  
Author(s):  
Ethan J. Nowak ◽  
Matthias G. Imhof
Keyword(s):  
Radon Transform ◽  
Seismic Data ◽  
Transform Domain ◽  
Multiple Reflections ◽  
Avo Analysis ◽  
Amplitude Versus Offset ◽  
Amplitude Preservation ◽  
Amplitude Versus

This study examines the effect of filtering in the Radon transform domain on reflection amplitudes. Radon filters are often used for removal of multiple reflections from normal moveout-corrected seismic data. The unweighted solution to the Radon transform reduces reflection amplitudes at both near and far offsets due to a truncation effect. However, the weighted solutions to the transform produce localized events in the transform domain, which minimizes this truncation effect. Synthetic examples suggest that filters designed in the Radon domain based on a weighted solution to the linear, parabolic, or hyperbolic transforms preserve the near- and far-offset reflection amplitudes while removing the multiples; whereas the unweighted solutions diminish reflection amplitudes which may distort subsequent amplitude-versus-offset (AVO) analysis.

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