The quality of the surface‐consistency assumption in short‐wavelength static correction

Geophysics ◽  
2004 ◽  
Vol 69 (4) ◽  
pp. 1091-1101 ◽  
Author(s):  
Gabriel Perez ◽  
Ken Larner
Keyword(s):  
Surface Layer ◽  
Seismic Data ◽  
Fresnel Zone ◽  
Ray Theory ◽  
Lateral Variation ◽  
Near Surface ◽  
Static Correction ◽  
Surface Models ◽  
Time Distortion

Founded on the assumption of surface consistency, reflection‐based residual‐statics correct for the time distortions in seismic data arising from rapid near‐surface variations. The assumption is founded on a vertical‐path, ray‐theoretical model of wave propagation in the near surface. Since ray theory does not hold for models with rapid spatial variation, we resort to finite‐difference modeling to study the influence of wave‐theoretical aspects on the character of time distortions and the validity of the surface‐consistency assumption. For near‐surface models that are admittedly simple and idealized, we find that the character of time distortions is highly influenced by a wavefront‐healing phenomenon whose strength depends on the ratio of the size of the frequency‐dependent Fresnel zone to the wavelength of lateral variation in the model. As experienced in practice, the quality of the surface‐consistency assumption degrades with increasing ratio of spreadlength to reflector depth. The validity of the assumption is best for longer‐wavelength anomalies in a weathering layer that is relatively thin. Wavefront healing, however, limits significantly the time‐distortion problem where the weathering layer is relatively thick. Interestingly, wavefront healing also helps to reduce the size of the time‐distortion problem when the velocity in the surface layer is large relative to that in the layers beneath, such as in areas of permafrost.

Analysis and Application on Frequency-Response Charateristic Based on Multi-Elements in Near-Surface

2014 ◽  
Vol 490-491 ◽  
pp. 1548-1552
Author(s):  
Zhi Xin Di
Keyword(s):  
Surface Layer ◽  
Seismic Data ◽  
Yellow River ◽  
Source Area ◽  
Yellow River Delta ◽  
Single Shot ◽  
Near Surface ◽  
Explosive Source ◽  
Layer Velocity

With the continuously process of prospecting program, our land exploration enter into activity lithostratigrapgy stage. For searching medium and small or subtle reservior, higher seismic data discernibility must be needed. In the explosive source area, surface layer velocity, shot lithology and ghost interface are the three key elements influencing the shot frequency. In view of the trait that the quality of single shot has apparently difference causing by near surface layer Yellow River Delta multiple lithology alternating deposits, we study the characteristics of frequency reponse to lithology and ghost by microseismogram log data, to provide reliable basis for scientific select shooting parameter.

scholarly journals Time-lapse difference static correction using prestack crosscorrelations: 4D seismic image enhancement case from Ketzin

Geophysics ◽  
2014 ◽  
Vol 79 (6) ◽  
pp. B243-B252 ◽  
Author(s):  
Peter Bergmann ◽  
Artem Kashubin ◽  
Monika Ivandic ◽  
Stefan Lüth ◽  
Christopher Juhlin
Keyword(s):  
Seismic Data ◽  
Time Lapse ◽  
Data Sets ◽  
Storage Site ◽  
Data Set ◽  
Near Surface ◽  
Static Correction ◽  
Seismic Image ◽  
Static Corrections ◽  
4D Seismic

A method for static correction of time-lapse differences in reflection arrival times of time-lapse prestack seismic data is presented. These arrival-time differences are typically caused by changes in the near-surface velocities between the acquisitions and had a detrimental impact on time-lapse seismic imaging. Trace-to-trace time shifts of the data sets from different vintages are determined by crosscorrelations. The time shifts are decomposed in a surface-consistent manner, which yields static corrections that tie the repeat data to the baseline data. Hence, this approach implies that new refraction static corrections for the repeat data sets are unnecessary. The approach is demonstrated on a 4D seismic data set from the Ketzin [Formula: see text] pilot storage site, Germany, and is compared with the result of an initial processing that was based on separate refraction static corrections. It is shown that the time-lapse difference static correction approach reduces 4D noise more effectively than separate refraction static corrections and is significantly less labor intensive.

The Role of Legacy Seismic in Enhancing the Image in the Current Seismic Data – Abu Dhabi: Case Study

2021 ◽  
Author(s):  
Ramy Elasrag ◽  
Thuraya Al Ghafri ◽  
Faaeza Al Katheer ◽  
Yousuf Al-Aufi ◽  
Ivica Mihaljevic ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Survey ◽  
Surface Model ◽  
Noise Attenuation ◽  
Near Surface ◽  
Velocity Models ◽  
Multiple Attenuation ◽  
Seismic Image ◽  
Seismic Acquisition

Abstract Acquiring surface seismic data can be challenging in areas of intense human activities, due to presence of infrastructures (roads, houses, rigs), often leaving large gaps in the fold of coverage that can span over several kilometers. Modern interpolation algorithms can interpolate up to a certain extent, but quality of reconstructed seismic data diminishes as the acquisition gap increases. This is where vintage seismic acquisition can aid processing and imaging, especially if previous acquisition did not face the same surface obstacles. In this paper we will present how the legacy seismic survey has helped to fill in the data gaps of the new acquisition and produced improved seismic image. The new acquisition survey is part of the Mega 3D onshore effort undertaken by ADNOC, characterized by dense shot and receiver spacing with focus on full azimuth and broadband. Due to surface infrastructures, data could not be completely acquired leaving sizable gap in the target area. However, a legacy seismic acquisition undertaken in 2014 had access to such gap zones, as infrastructures were not present at the time. Legacy seismic data has been previously processed and imaged, however simple post-imaging merge would not be adequate as two datasets were processed using different workflows and imaging was done using different velocity models. In order to synchronize the two datasets, we have processed them in parallel. Data matching and merging were done before regularization. It has been regularized to radial geometry using 5D Matching Pursuit with Fourier Interpolation (MPFI). This has provided 12 well sampled azimuth sectors that went through surface consistent processing, multiple attenuation, and residual noise attenuation. Near surface model was built using data-driven image-based static (DIBS) while reflection tomography was used to build the anisotropic velocity model. Imaging was done using Pre-Stack Kirchhoff Depth Migration. Processing legacy survey from the beginning has helped to improve signal to noise ratio which assisted with data merging to not degrade the quality of the end image. Building one near surface model allowed both datasets to match well in time domain. Bringing datasets to the same level was an important condition before matching and merging. Amplitude and phase analysis have shown that both surveys are aligned quite well with minimal difference. Only the portion of the legacy survey that covers the gap was used in the regularization, allowing MPFI to reconstruct missing data. Regularized data went through surface multiple attenuation and further noise attenuation as preconditioning for migration. Final image that is created using both datasets has allowed target to be imaged better.

SEISMIC DATA ENHANCEMENT—A CASE HISTORY

Geophysics ◽  
1960 ◽  
Vol 25 (1) ◽  
pp. 283-311 ◽  
Author(s):  
R. J. Graebner
Keyword(s):  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Wave Length ◽  
Frequency Range ◽  
Near Surface ◽  
Theory To Practice ◽  
Special Character ◽  
Strong Surface ◽  
Data Processing Methods

The theory relating to many methods—for example, multiple seismometer techniques—which the geophysicist may control to improve record quality is well known. However, its application has not been fully exploited. An example of the reduction of theory to practice in one area characterized by poor records is presented. It comprises a series of analytical tests designed to discover the cause of poor records, to examine the effect of each variable on the signal‐to‐noise ratio, and to evaluate the solutions predicted by theory. The tests showed that the poor record quality was attributable chiefly to relatively strong surface and near‐surface waves propagating outward from the shot. Wave length filtering by means of suitable shot and seismometer patterns, and compositing through data processing methods, greatly improved record quality and permitted magnetic recording of reflected signals over a broad frequency range. The tests established, in the allotted time, that the quality of the data would meet clearly specified standards of performance. Experience has shown that better seismic data can generally be obtained when the design of techniques is based on the special character of the signal and noise determined from simple tests rather than when the design is based on general assumptions.

Metallographic Study of Mesostructure-Ordered Plasma Ceramic Coatings

2017 ◽  
Vol 743 ◽  
pp. 118-123 ◽  
Author(s):  
Valery I. Bogdanovich ◽  
Mikhail G. Giorbelidze
Keyword(s):  
Surface Layer ◽  
Quantitative Evaluation ◽  
Ceramic Coatings ◽  
Ordered Structure ◽  
Narrow Fraction ◽  
Quantitative Criterion ◽  
Coating Structure ◽  
Near Surface ◽  
Metallographic Study

This article provides the reader with results of the study of mesostructure ordered plasma ceramic coatings derived from narrow-fraction powders under optimum modes for this fraction. It is noted that it is succeeded to implement mesostructure ordering of coatings eliminating the formation of continuous columnar structures by means of spraying mode control. It is proven that it is possible to get formation of nanocolumnar structures in a near surface layer, and these structures provide bonds damping between clusters under alternating force and thermal loads of coated parts. To evaluate the quality of formed ordered structure, a quantitative criterion—mesostructure ordering coefficient—is used. The Methods of quantitative evaluation of mesoordering of coating structure has been developed.

Interferometric application of static corrections

Geophysics ◽  
2012 ◽  
Vol 77 (1) ◽  
pp. Q1-Q13 ◽  
Author(s):  
David C. Henley
Keyword(s):  
Seismic Data ◽  
S Wave ◽  
Near Surface ◽  
Persistent Problem ◽  
Static Correction ◽  
Reflection Seismic ◽  
Special Cases ◽  
Surface Irregularities ◽  
Static Corrections ◽  
Surface Angle

Correcting reflection seismic data for the effects of near-surface irregularities is a persistent problem usually addressed at least partly by static corrections applied to traces. However, there are areas where static corrections are ineffective because basic assumptions are violated. The assumptions which fail most often are surface consistency and stationarity, which are central to the concept of static corrections. To address this failure, I mapped raw seismic traces into the radial trace domain and gathered the radial traces by common surface angle. Then I imposed a more general constraint, raypath consistency, which simultaneously introduces nonstationarity. Conventional static correction also assumes implicitly that reflection events consist of single discrete arrivals. This is not true, however, in regions where near-surface multipathing and scattering complicate reflection event waveforms. Borrowing from recent work in seismic inferometry, I removed the single-arrival assumption by using trace crosscorrelations to estimate and deconvolve surface functions from traces, rather than applying time shifts. The entire crosscorrelation function is used in every case, so both timing and waveform variations are removed by the deconvolution. The operation is applied in the common-angle domain, so it is raypath consistent and nonstationary. The method, dubbed “raypath interferometry,” was applied successfully to a set of 2D Arctic field data with serious surface consistency and multipath problems, and to a set of 3C 2D land data with very large S-wave receiver statics. Although intended primarily for use on seismic data for which conventional statics corrections fail, raypath interferometry can be used on any seismic data; its assumptions include single-arrival events and surface consistency as special cases.

Recombination Characteristics of Single-Crystalline Silicon Wafers with a Damaged Near-Surface Layer

2013 ◽  
Vol 58 (2) ◽  
pp. 142-150 ◽  
Author(s):  
A.V. Sachenko ◽  
◽  
V.P. Kostylev ◽  
V.G. Litovchenko ◽  
V.G. Popov ◽  
...  
Keyword(s):  
Surface Layer ◽  
Crystalline Silicon ◽  
Silicon Wafers ◽  
Single Crystalline Silicon ◽  
Near Surface ◽  
Single Crystalline
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