Three-dimensional seismic-reflection imaging of a shallow buried paleochannel

Geophysics ◽  
2008 ◽  
Vol 73 (5) ◽  
pp. B85-B98 ◽  
Author(s):  
Gian Luigi Fradelizio ◽  
Alan Levander ◽  
Colin A. Zelt
Keyword(s):  
Water Saturation ◽  
Three Dimensional ◽  
Nonaqueous Phase Liquids ◽  
Reflection Seismology ◽  
Data Set ◽  
Mechanical Heterogeneity ◽  
Shallow Subsurface ◽  
Reflection Data ◽  
Air Force Base ◽  
Well Data

A suite of reflection seismology investigations of the shallow subsurface was conducted at Hill Air Force Base, Ogden, Utah, at a groundwater contamination site with very large subsurface mechanical heterogeneity. The investigations were designed to expand and improve understanding of the subsurface environment developed from well data and previous seismic investigations. The goal of the investigations was to image the sides and bottom of a paleochannel eroded in a clay layer [Formula: see text] below the surface. The paleochannel is filled with a mix of sands, clays, and gravels of different compaction and water saturation. The paleochannel acts as a contaminant trap for dense nonaqueous-phase liquids (DNAPLs). Therefore, a detailed map of its geometry, lateral boundaries, and depth is crucial to remediation efforts. The results of processing a 3D reflection data set over the channel showed that it is possible to image and delineate the geometry and depth of a very shallow structure. Seismic results agreed well with the available well data in the deepest part of the buried paleochannel. The map of the channel derived from seismic data replaces the need for many wells.

Minimizing field operations in shallow 3‐D seismic reflection surveying

Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1761-1773 ◽  
Author(s):  
Roman Spitzer ◽  
Alan G. Green ◽  
Frank O. Nitsche
Keyword(s):  
Seismic Reflection ◽  
Cost Effective ◽  
Unconsolidated Sediments ◽  
Data Set ◽  
Seismic Reflection Data ◽  
Northern Switzerland ◽  
Shallow Subsurface ◽  
Reflection Data ◽  
Effective Manner ◽  
Original Survey

By appropriately decimating a comprehensive shallow 3‐D seismic reflection data set recorded across unconsolidated sediments in northern Switzerland, we have investigated the potential and limitations of four different source‐receiver acquisition patterns. For the original survey, more than 12 000 shots and 18 000 receivers deployed on a [Formula: see text] grid resulted in common midpoint (CMP) data with an average fold of ∼40 across a [Formula: see text] area. A principal goal of our investigation was to determine an acquisition strategy capable of producing reliable subsurface images in a more efficient and cost‐effective manner. Field efforts for the four tested acquisition strategies were approximately 50%, 50%, 25%, and 20% of the original effort. All four data subsets were subjected to a common processing sequence. Static corrections, top‐mute functions, and stacking velocities were estimated individually for each subset. Because shallow reflections were difficult to discern on shot and CMP gathers generated with the lowest density acquisition pattern (20% field effort) such that dependable top‐mute functions could not be estimated, data resulting from this acquisition pattern were not processed to completion. Of the three fully processed data subsets, two (50% field effort and 25% field effort) yielded 3‐D migrated images comparable to that derived from the entire data set, whereas the third (50% field effort) resulted in good‐quality images only in the shallow subsurface because of a lack of far‐offset data. On the basis of these results, we concluded that all geological objectives associated with our particular study site, which included mapping complex lithological units and their intervening shallow dipping boundaries, would have been achieved by conducting a 3‐D seismic reflection survey that was 75% less expensive than the original one.

Waveform tomography at a groundwater contamination site: Surface reflection data

Geophysics ◽  
2007 ◽  
Vol 72 (5) ◽  
pp. G45-G55 ◽  
Author(s):  
Fuchun Gao ◽  
Alan Levander ◽  
R. Gerhard Pratt ◽  
Colin A. Zelt ◽  
Gian-Luigi Fradelizio
Keyword(s):  
Groundwater Contamination ◽  
Nonaqueous Phase Liquids ◽  
Seismic Profiles ◽  
Lateral Velocity ◽  
Data Set ◽  
Surface Reflection ◽  
Traveltime Tomography ◽  
Velocity Models ◽  
Reflection Data ◽  
Waveform Tomography

We have applied acoustic-waveform tomography to 45 2D seismic profiles to image the 3D geometry of a buried paleochannel at a groundwater-contamination site at Hill Air Force Base in Utah. The paleochannel, which is incised into an alluvium-covered clay aquitard, acts as a trap for dense nonaqueous-phase liquids (DNAPLs) that contaminate the shallowest groundwater system in the study area. The 2D profiles were extracted from a 3D surface reflection data set. First-arrival traveltime tomography provided initial velocity models for the waveform tomography. We inverted for six frequency components in the band [Formula: see text] of the direct and refracted waves to produce 45 2D velocity models. The flanks and bottom of a channel with a maximum depth of about [Formula: see text] were well modeled in most of the 45 parallel 2D slices, which allowed us to construct a 3D image of the channel by combining and interpolating between the 45 image slices. The 3D model of the channel will be useful for siting extraction wells within the site remediation program. The alluvium that fills the channel showed marked vertical and lateral velocity heterogeneity. Traveltime tomography and waveform tomography can be complementary approaches. Used together, they can provide high-resolution images of complicated shallow structures.

Broadband receiver response from dual‐streamer data and applications in deep reflection seismology

Geophysics ◽  
1996 ◽  
Vol 61 (1) ◽  
pp. 232-243 ◽  
Author(s):  
Satish C. Singh ◽  
R. W. Hobbs ◽  
D. B. Snyder
Keyword(s):  
Signal To Noise Ratio ◽  
Spectral Response ◽  
Synthetic Data ◽  
Real Data ◽  
Reflection Seismology ◽  
Data Set ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Streamer Data ◽  
Lower Crustal

A method to process dual‐streamer data with under and over configuration is presented. The method combines the results of dephase‐sum and dephase‐subtraction methods. In the dephase methods, the response of one streamer is time shifted so that the primary arrivals on both streamers are aligned, and these responses are then summed or subtracted. The method provides a broad spectral response from dual‐streamer data and increases the signal‐to‐noise ratio by a factor of 1.5. Testing was done on synthetic data and then applied to a real data set collected by the British Institutions Reflection Profiling Syndicate (BIRPS). Its application to a deep seismic reflection data set from the British Isles shows that the reflections from the lower crust contain frequencies up to 80 Hz, suggesting that some of the lower crustal reflectors may have sharp boundaries and could be 20–30 m thick.

Efficient acquisition, processing, and interpretation strategy for shallow 3D seismic surveying: A Case Study

Geophysics ◽  
2003 ◽  
Vol 68 (6) ◽  
pp. 1792-1806 ◽  
Author(s):  
Roman Spitzer ◽  
Frank O. Nitsche ◽  
Alan G. Green ◽  
Heinrich Horstmeyer
Keyword(s):  
Interpolation Method ◽  
Seismic Facies ◽  
3D Seismic ◽  
Data Set ◽  
Processing Scheme ◽  
Seismic Reflection Data ◽  
Shallow Subsurface ◽  
Reflection Data ◽  
Seismic Surveying ◽  
Sand And Gravel

A new 3D seismic reflection data set has been used to map the shallow subsurface beneath a key region of the Swiss Rhine Valley. Seismic signals generated by a pipegun were recorded with single 30‐Hz geophones distributed across a 277.5 × 357.0‐m area. The dense distribution of sources and receivers resulted in a binning grid of 2.12 × 2.12 m and an average fold of ∼22. To improve the visibility and continuity of reflections, a novel processing strategy was designed and applied to the acquired data. A combination of regridding and sharing traces in the common midpoint (CMP) domain resulted in increased S/N ratios with only minor loss of resolution. This prestack interpolation method yielded composite CMPs distributed on a 1.5 × 1.5‐m binning grid and an increased average fold of ∼44. The composite CMPs were subjected to a combined linear and hyperbolic τ–p processing scheme that led to the effective separation of reflections from source‐generated noise. Finally, 3D depth migration of the stacked data produced high‐resolution images of the subsurface from ∼15 to ∼130 m depth. On the basis of characteristic seismic facies and information from nearby boreholes, four principal lithological units were identified. At increasing depths they were glaciofluvial sand and gravel, glaciolacustrine clay and silt, morainal deposits, and sandstone basement. These lithological units were separated by three principal reflecting boundaries that were mapped through the data volume using semiautomatic tracking procedures. The deepest boundary defined a trough‐shaped basement structure.

Three-dimensional seismic-while-drilling (SWD) migration in the angular frequency domain

Geophysics ◽  
2005 ◽  
Vol 70 (6) ◽  
pp. S111-S120
Author(s):  
Fabio Rocca ◽  
Massimiliano Vassallo ◽  
Giancarlo Bernasconi
Keyword(s):  
Frequency Domain ◽  
Three Dimensional ◽  
Synthetic Data ◽  
Vertical Axis ◽  
Velocity Model ◽  
Angular Frequency ◽  
Data Set ◽  
Surface Reflection ◽  
Reflection Data ◽  
Seismic Depth Migration

Seismic depth migration back-propagates seismic data in the correct depth position using information about the velocity of the medium. Usually, Kirchhoff summation is the preferred migration procedure for seismic-while-drilling (SWD) data because it can handle virtually any configuration of sources and receivers and one can compensate for irregular spatial sampling of the array elements (receivers and sources). Under the assumption of a depth-varying velocity model, with receivers arranged along a horizontal circumference and sources placed along the central vertical axis, we reformulate the Kirchhoff summation in the angular frequency domain. In this way, the migration procedure becomes very efficient because the migrated volume is obtained by an inverse Fourier transform of the weighted data. The algorithm is suitable for 3D SWD acquisitions when the aforementioned hypothesis holds. We show migration tests on SWD synthetic data, and we derive solutions to reduce the migration artifacts and to control aliasing. The procedure is also applied on a real 3D SWD data set. The result compares satisfactorily with the seismic stack section obtained from surface reflection data and with the results from traditional Kirchhoff migration.

scholarly journals Three-dimensional shape and structure of the Susitna basin, south-central Alaska, from geophysical data

Geosphere ◽  
2020 ◽  
Vol 16 (4) ◽  
pp. 969-990
Author(s):  
Anjana K. Shah ◽  
Jeffrey D. Phillips ◽  
Kristen A. Lewis ◽  
Richard G. Stanley ◽  
Peter J. Haeussler ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Seismic Reflection ◽  
Three Dimensional ◽  
Fold Axis ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
South Central ◽  
Dimensional Shape ◽  
Well Data ◽  
Three Dimensional Shape

Abstract We use gravity, magnetic, seismic reflection, well, and outcrop data to determine the three-dimensional shape and structural features of south-central Alaska’s Susitna basin. This basin is located within the Aleutian-Alaskan convergent margin region and is expected to show effects of regional subduction zone processes. Aeromagnetic data, when filtered to highlight anomalies associated with sources within the upper few kilometers, show numerous linear northeast-trending highs and some linear north-trending highs. Comparisons to seismic reflection and well data show that these highs correspond to areas where late Paleocene to early Eocene volcanic layers have been locally uplifted due to folding and/or faulting. The combined magnetic and seismic reflection data suggest that the linear highs represent northeast-trending folds and north-striking faults. Several lines of evidence suggest that the northeast-trending folds formed during the middle Eocene to early Miocene and may have continued to be active in the Pliocene. The north-striking faults, which in some areas appear to cut the northeast-trending folds, show evidence of Neogene and probable modern movement. Gravity data facilitate estimates of the shape and depth of the basin. This was accomplished by separating the observed gravity anomaly into two components—one representing low-density sedimentary fill within the basin and one representing density heterogeneities within the underlying crystalline basement. We then used the basin anomaly, seismic reflection data, and well data to estimate the depth of the basin. Together, the magnetic, gravity, and reflection seismic analyses reveal an asymmetric basin comprising sedimentary rock over 4 km thick with steep, fault-bounded sides to the southwest, west, and north and a mostly gentle rise toward the east. Relations to the broader tectonic regime are suggested by fold axis orientations within the Susitna basin and neighboring Cook Inlet basin, which are roughly parallel to the easternmost part of the Alaska-Aleutian trench and associated Wadati-Benioff zone as it trends from northeast to north-northeast to northeast. An alignment between forearc basin folds and the subduction zone trench has been observed at other convergent margins, attributed to strain partitioning generated by regional rheologic variations that are associated with the subducting plate and arc magmatism. The asymmetric shape of the basin, especially its gentle rise to the east, may reflect uplift associated with flat-slab subduction of the Yakutat microplate, consistent with previous work that suggested Yakutat influence on the nearby Talkeetna Mountains and western Alaska Range. Yakutat subduction may also have contributed to Neogene and later reverse slip along north-striking faults within the Susitna basin.

Three-dimensional image analysis and visualization in confocal light microscopy

1993 ◽  
Vol 51 ◽  
pp. 158-159
Author(s):  
J. K. Samarabandu ◽  
R. Acharya ◽  
D. R. Pareddy ◽  
P. C. Cheng
Keyword(s):  
Depth Perception ◽  
Computer Graphic ◽  
Three Dimensional ◽  
Cellular Organization ◽  
Data Set ◽  
Computational Burden ◽  
Interactive Operation ◽  
Cell Organization ◽  
Confocal Images ◽  
3D Digitization

In the study of cell organization in a maize meristem, direct viewing of confocal optical sections in 3D (by means of 3D projection of the volumetric data set, Figure 1) becomes very difficult and confusing because of the large number of nucleus involved. Numerical description of the cellular organization (e.g. position, size and orientation of each structure) and computer graphic presentation are some of the solutions to effectively study the structure of such a complex system. An attempt at data-reduction by means of manually contouring cell nucleus in 3D was reported (Summers et al., 1990). Apart from being labour intensive, this 3D digitization technique suffers from the inaccuracies of manual 3D tracing related to the depth perception of the operator. However, it does demonstrate that reducing stack of confocal images to a 3D graphic representation helps to visualize and analyze complex tissues (Figure 2). This procedure also significantly reduce computational burden in an interactive operation.

EMCAT: An automatic image-processing system for electron-microscopic tomography

1994 ◽  
Vol 52 ◽  
pp. 418-419
Author(s):  
Weiping Liu ◽  
John W. Sedat ◽  
David A. Agard
Keyword(s):  
Image Processing ◽  
Structural Information ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Processing System ◽  
Electron Microscopic ◽  
Data Set ◽  
Ordered Structures ◽  
Automatic Image Processing ◽  
Em Tomography

Any real world object is three-dimensional. The principle of tomography, which reconstructs the 3-D structure of an object from its 2-D projections of different view angles has found application in many disciplines. Electron Microscopic (EM) tomography on non-ordered structures (e.g., subcellular structures in biology and non-crystalline structures in material science) has been exercised sporadically in the last twenty years or so. As vital as is the 3-D structural information and with no existing alternative 3-D imaging technique to compete in its high resolution range, the technique to date remains the kingdom of a brave few. Its tedious tasks have been preventing it from being a routine tool. One keyword in promoting its popularity is automation: The data collection has been automated in our lab, which can routinely yield a data set of over 100 projections in the matter of a few hours. Now the image processing part is also automated. Such automations finish the job easier, faster and better.

Harmonic Analysis on Low Quality Tidal Data

2014 ◽  
Author(s):  
Joost den Haan
Keyword(s):  
Harmonic Analysis ◽  
Three Dimensional ◽  
Measurement Data ◽  
Tidal Energy ◽  
Energy Yield ◽  
Profile Measurement ◽  
Current Profile ◽  
Tidal Power ◽  
Data Set ◽  
Tidal Forcing

The aim of the study is to devise a method to conservatively predict a tidal power generation based on relatively short current profile measurement data sets. Harmonic analysis on a low quality tidal current profile measurement data set only allowed for the reliable estimation of a limited number of constituents leading to a poor prediction of tidal energy yield. Two novel, but very different approaches were taken: firstly a quasi response function is formulated which combines the currents profiles into a single current. Secondly, a three dimensional vectorial tidal forcing model was developed aiming to support the harmonic analysis with upfront knowledge of the actual constituents. The response based approach allowed for a reasonable prediction. The vectorial tidal forcing model proved to be a viable start for a full featuring numerical model; even in its initial simplified form it could provide more insight than the conventional tidal potential models.

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