SOME CHARACTERISTICS OF MARINE SPARKER SEISMIC DATA

Geophysics ◽  
1972 ◽  
Vol 37 (3) ◽  
pp. 462-470 ◽  
Author(s):  
F. T. Allen
Keyword(s):  
Seismic Data ◽  
Water Layer ◽  
Seismic Survey ◽  
Multiple Reflections ◽  
Time Profiles ◽  
Survey Technique ◽  
Recording Conditions ◽  
Single Detector ◽  
Marine Seismic ◽  
The Relationship

The marine seismic survey technique of frequent recordings with a single detector group can provide intricate details valuable to relatively shallow investigations. Velocities may be computed from time anomalies, under certain circumstances. The extent of multiple energy response is an indication that the 100,000-joule source is strong enough for the purpose. Recognizable minor details in primary reflections are important clues in identifying related multiple reflections. Bounces off the underside of the water layer are rarely found. The pattern and character of reflections are influenced by recording conditions; thus, the relationship between recorded events and sedimentary beds is not simple. Seismic time profiles frequently give wrong impressions of structural attitudes because of the horizontal‐to‐vertical exaggeration, time anomalies, and multiple reflections, as well as the usual effects of velocity differences. The interpreted cross‐section gives a reasonably correct (even if velocities are assumed) impression of structure; the profile often does not.

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.

A MARINE SEISMIC MODEL

Geophysics ◽  
1956 ◽  
Vol 21 (2) ◽  
pp. 320-336 ◽  
Author(s):  
George P. Sarrafian
Keyword(s):  
Water Layer ◽  
Multiple Reflection ◽  
Air Bubbles ◽  
Seismic Model ◽  
Multiple Reflections ◽  
Marine Seismic ◽  
Search For Information

A model for the study of marine seismic phenomena is described. Study of multiple‐reflection phenomena forms the basis for the course of experiments. It is shown that the multiple‐reflection phenomenon of a disturbance with slowly decaying amplitude may be duplicated in the model. Multiple‐reflection problems are studied in which the bottom of the water layer is tilted or thin. A mass of air bubbles is shown to be of use in attenuating multiple reflections. The possible application of the marine model in a search for information about certain problems in field prospecting is suggested.

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.

A dictionary learning method for seismic data compression

Geophysics ◽  
2021 ◽  
pp. 1-83
Author(s):  
Mohammed Outhmane Faouzi Zizi ◽  
Pierre Turquais
Keyword(s):  
Data Storage ◽  
Compression Ratio ◽  
Dictionary Learning ◽  
Seismic Data ◽  
Superior Performance ◽  
Seismic Survey ◽  
Learning Method ◽  
Data Set ◽  
Wide Range ◽  
Marine Seismic

For a marine seismic survey, the recorded and processed data size can reach several terabytes. Storing seismic data sets is costly and transferring them between storage devices can be challenging. Dictionary learning has been shown to provide representations with a high level of sparsity. This method stores the shape of the redundant events once, and represents each occurrence of these events with a single sparse coefficient. Therefore, an efficient dictionary learning based compression workflow, which is specifically designed for seismic data, is developed here. This compression method differs from conventional compression methods in three respects: 1) the transform domain is not predefined but data-driven; 2) the redundancy in seismic data is fully exploited by learning small-sized dictionaries from local windows of the seismic shot gathers; 3) two modes are proposed depending on the geophysical application. Based on a test seismic data set, we demonstrate superior performance of the proposed workflow in terms of compression ratio for a wide range of signal-to-residual ratios, compared to standard seismic data methods, such as the zfp software or algorithms from the Seismic Unix package. Using a more realistic data set of marine seismic acquisition, we evaluate the capability of the proposed workflow to preserve the seismic signal for different applications. For applications such as near-real time transmission and long-term data storage, we observe insignificant signal leakage on a 2D line stack when the dictionary learning method reaches a compression ratio of 24.85. For other applications such as visual QC of shot gathers, our method preserves the visual aspect of the data even when a compression ratio of 95 is reached.

Ray‐tracing‐based prediction and subtraction of water‐layer multiples

Geophysics ◽  
1990 ◽  
Vol 55 (4) ◽  
pp. 443-451 ◽  
Author(s):  
Andrew J. Calvert
Keyword(s):  
Ray Tracing ◽  
Seismic Data ◽  
Computational Cost ◽  
Water Layer ◽  
Computational Effort ◽  
Lateral Variation ◽  
Multiple Reflections ◽  
Seafloor Topography ◽  
Arrival Times ◽  
Data Matching

Many methods of multiple suppression break down when the structure that produces the reverberation possesses significant lateral variation; a common example of this situation occurs in marine data with the multiple reflections that are generated by seafloor topography. Such multiples may be suppressed by techniques based upon wave‐equation extrapolation; the recorded seismic data are mathematically propagated through a simulated water layer to generate a set of multiple arrivals which may, after data matching, be subtracted. However, the computational effort required to propagate prestack data to a laterally varying datum is very large. In this paper, a method of suppressing selected multiples with arbitrary moveout is presented. In order to reduce the computational cost, prediction of the multiple arrival times is performed by ray tracing through a model of the laterally varying water layer and, possibly, the subsurface. An estimate of the multiple waveform on each trace is obtained by stacking a window of data about the calculated arrival times. The multiple arrival can then be attenuated by subtracting this wavelet from each trace in the prestack gather from which the estimate is derived. In practice, calculations of the variation in multiple amplitude and of any errors in the moveout correction require the multiple reflections to be of comparable, or higher, amplitude than contemporary primary events, a situation that is often the case where multiple contamination is a problem.

WATER REVERBERATIONS—THEIR NATURE AND ELIMINATION

Geophysics ◽  
1959 ◽  
Vol 24 (2) ◽  
pp. 233-261 ◽  
Author(s):  
Milo M. Backus
Keyword(s):  
Seismic Data ◽  
Structural Information ◽  
Water Layer ◽  
Original Data ◽  
Present Form ◽  
Linear Filtering ◽  
Inverse Filtering ◽  
Multiple Reflections ◽  
Filtering Techniques

In offshore shooting the validity of previously recorded seismic data has been severely limited by multiple reflections within the water layer. The magnitude of this problem is dependent on the thickness and the nature of the boundaries of the water layer. The effect of the water layer is treated as a linear filtering mechanism, and it is suggested that most apparent water reverberation records probably contain some approximate subsurface structural information, even in their present form. The use of inverse filtering techniques for the removal or attenuation of the water reverberation effect is discussed. Examples show the application of the technique to conventional magnetically recorded offshore data. It has been found that the effectiveness of the method is strongly dependent on the instrumental parameters used in the recording of the original data.

Quantitative thickness estimates from the spectral response of AVO measurements

Geophysics ◽  
2008 ◽  
Vol 73 (1) ◽  
pp. C1-C6 ◽  
Author(s):  
Ethan J. Nowak ◽  
Herbert W. Swan ◽  
Dave Lane
Keyword(s):  
Frequency Band ◽  
Seismic Data ◽  
Spectral Decomposition ◽  
Spectral Response ◽  
Seismic Survey ◽  
Decomposition Technique ◽  
Target Interval ◽  
Optimization Scheme ◽  
Resolution Limits ◽  
Marine Seismic

This study is motivated by the necessity to quantitatively characterize subtuned reservoirs. The conventional autocorrelation-based spectral-decomposition technique uses frequency notches to calculate vertical traveltime thickness of a layer of dipole reflectivity. Those notches tend to move outside the usable frequency band of the seismic data as the layer exceeds the tuning threshold of the wavelet. Assuming wavelet stationarity and nondipole reflectivity, a similar analysis performed on a crosscorrelation between an intercept and gradient trace extends the resolution limits to one-half the tuning threshold. That is a major improvement; however, many economic reservoirs still do not meet the half-tuning requirement. Such thin reservoirs led to the development of an optimization scheme. This approach, which does not require any wavelet stationarity or reflectivity assumptions, theoretically is not limited by the thickness of the target interval. The optimization scheme was applied successfully to a marine seismic survey in an attempt to estimate the traveltime thickness of a chalk reservoir.

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