Pitfalls in processing near-surface reflection-seismic data: Beware of static corrections and migration

2015 ◽  
Vol 34 (11) ◽  
pp. 1382-1385 ◽  
Author(s):  
W. Frei ◽  
R. Bauer ◽  
Ph. Corboz ◽  
D. Martin
Keyword(s):  
Seismic Data ◽  
Near Surface ◽  
Surface Reflection ◽  
Reflection Seismic ◽  
Static Corrections ◽  
And Migration

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.

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.

scholarly journals Muting the noise cone in near‐surface reflection data: An example from southeastern Kansas

Geophysics ◽  
1998 ◽  
Vol 63 (4) ◽  
pp. 1332-1338 ◽  
Author(s):  
Gregory S. Baker ◽  
Don W. Steeples ◽  
Matt Drake
Keyword(s):  
Data Processing ◽  
Seismic Data ◽  
Hydrocarbon Exploration ◽  
Seismic Reflection Profile ◽  
Seismic Data Processing ◽  
Near Surface ◽  
Surface Reflection ◽  
Reflection Data ◽  
Data Volume ◽  
Total Data

A 300-m near‐surface seismic reflection profile was collected in southeastern Kansas to locate a fault(s) associated with a recognized stratigraphic offset on either side of a region of unexposed bedrock. A substantial increase in the S/N ratio of the final stacked section was achieved by muting all data arriving in time after the airwave. Methods of applying traditional seismic data processing techniques to near‐surface data (200 ms of data or less) often differ notably from hydrocarbon exploration‐scale processing (3–4 s of data or more). The example of noise cone muting used is contrary to normal exploration‐scale seismic data processing philosophy, which is to include all data containing signal. The noise cone mute applied to the data removed more than one‐third of the total data volume, some of which contains signal. In this case, however, the severe muting resulted in a higher S/N ratio in the final stacked section, even though some signal could be identified within the muted data. This example supports the suggestion that nontraditional techniques sometimes need to be considered when processing near‐surface seismic data.

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.

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.

Multidisciplinary study of the hanging wall of the Kiirunavaara iron ore deposit, northern Sweden

Geophysics ◽  
2012 ◽  
Vol 77 (6) ◽  
pp. B269-B285 ◽  
Author(s):  
Mai-Britt Jensen ◽  
Artem Kashubin ◽  
Christopher Juhlin ◽  
Sten-Åke Elming
Keyword(s):  
Seismic Data ◽  
Hanging Wall ◽  
Low Velocity ◽  
Contact Zones ◽  
Near Surface ◽  
Reflection Seismic ◽  
Imaging Results ◽  
Fracture Development ◽  
Weakness Zones ◽  
The Town

Potential weakness zones due to mining-related fracture development under the town of Kiruna, Sweden, have been investigated by integration of seismic, gravity, and petrophysical data. Reflection seismic data were acquired along two subparallel 2D profiles within the residential area of the town. The profiles of [Formula: see text], each oriented approximately east–west, nearly perpendicular to the general strike of the local geology, crossed several contact zones between quartz-bearing porphyries, a sequence of interchanging sedimentary rocks (siltstone, sandstone, conglomerate, and agglomerate), and metabasalt. The resulting reflection seismic sections revealed a strong east-dipping reflectivity that is imaged down to approximately 1.5 km. The location and orientation of major features agree well between the profiles and with the surface geology and known contact zones between the different rock types. Our imaging results, supported by traveltime modelling, indicate that the contact zones dip 40°–50° to the east. The deepest and the weakest reflections are associated with a [Formula: see text] dipping structure that is presumably related to the Kiirunavaara iron mineralization. Tomographic inversion of refracted arrivals revealed a more detailed image of the velocity distribution in the upper 100–200 m along the profiles, enabling us to identify near-surface low velocity zones. These could be possible weakness zones developed along the lithological contacts and within the geologic units. The structural image obtained from the seismic data was used to constrain data inversion along a 28 km long east–northeast to west–southwest-oriented gravity profile. The resulting density model indicates that the quartz-bearing porphyry in the hanging wall of the Kiirunavaara mineralization can be separated into two blocks oriented parallel to the ore body. One block has an unexpected low density, which could be an indication of extensive fracturing and deformation.

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