Ultra shallow seismic reflection in unconsolidated sediments: Rock physics base for data acquisition

1998 ◽  
Author(s):  
Ran Bachrach ◽  
Amos Nur
Keyword(s):  
Data Acquisition ◽  
Seismic Reflection ◽  
Rock Physics ◽  
Unconsolidated Sediments ◽  
Shallow Seismic

scholarly journals Depth characterization of shallow aquifers with seismic reflection, Part II—Prestack depth migration and field examples

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 98-109 ◽  
Author(s):  
John H. Bradford ◽  
D. S. Sawyer
Keyword(s):  
Seismic Reflection ◽  
Water Saturation ◽  
Compressional Wave ◽  
Unconsolidated Sediments ◽  
Prestack Depth Migration ◽  
Improve Image Quality ◽  
Depth Migration ◽  
Shallow Seismic ◽  
Partial Water

It is common in shallow seismic studies for the compressional‐wave velocity in unconsolidated sediments to increase by a factor of four or more at the transition from dry or partial water saturation to full saturation. Under these conditions, conventional NMO velocity analysis fails and leads to large depth and layer thickness estimates if the Dix equation is assumed valid. Prestack depth migration (PSDM) is a means of improving image accuracy. A comparison of PSDM with conventional NMO processing for three field examples from differing hydrogeologic environments illustrates that PSDM can significantly improve image quality and accuracy.

scholarly journals Recording seismic reflections using rigidly interconnected geophones

Geophysics ◽  
2001 ◽  
Vol 66 (6) ◽  
pp. 1838-1842 ◽  
Author(s):  
C. M. Schmeissner ◽  
K. T. Spikes ◽  
D. W. Steeples
Keyword(s):  
Wave Propagation ◽  
Data Acquisition ◽  
Seismic Reflection ◽  
Spatial Sampling ◽  
P Wave ◽  
Signal Distortion ◽  
Reflection And Refraction ◽  
First Arrival ◽  
The Cost ◽  
Seismic Reflections

Ultrashallow seismic reflection surveys require dense spatial sampling during data acquisition, which increases their cost. In previous efforts to find ways to reduce these costs, we connected geophones rigidly to pieces of channel iron attached to a farm implement. This method allowed us to plant the geophones in the ground quickly and automatically. The rigidly interconnected geophones used in these earlier studies detected first‐arrival energy along with minor interfering seismic modes, but they did not detect seismic reflections. To examine further the feasibility of developing rigid geophone emplacement systems to detect seismic reflections, we experimented with four pieces of channel iron, each 2.7 m long and 10 cm wide. Each segment was equipped with 18 geophones rigidly attached to the channel iron at 15‐cm intervals, and the spikes attached to all 18 geophones were pushed into the ground simultaneously. The geophones detected both refracted and reflected energy; however, no significant signal distortion or interference attributable to the rigid coupling of the geophones to the channel iron was observed in the data. The interfering seismic modes mentioned from the previous experiments were not detected, nor was any P‐wave propagation noted within the channel iron. These results show promise for automating and reducing the cost of ultrashallow seismic reflection and refraction surveys.

Delineating paleochannels using shallow seismic reflection

1997 ◽  
Vol 16 (11) ◽  
pp. 1671-1674 ◽  
Author(s):  
Richard D. Miller ◽  
Jianghai Xia
Keyword(s):  
Seismic Reflection ◽  
Shallow Seismic

scholarly journals Marine substrate response from the analysis of seismic attributes in CHIRP sub-bottom profiles

2017 ◽  
Vol 65 (3) ◽  
pp. 332-345 ◽  
Author(s):  
Larissa Felicidade Werkhauser Demarco ◽  
Antonio Henrique da Fontoura Klein ◽  
Jorge Antonio Guimarães de Souza
Keyword(s):  
Grain Size ◽  
Seismic Reflection ◽  
Ground Truth ◽  
Fine Sand ◽  
Seismic Attributes ◽  
Coarse Sand ◽  
Unconsolidated Sediments ◽  
Shallow Gas ◽  
Size Classes ◽  
Seismic Reflection Profiles

Abstract This paper presents an evaluation of the response of seismic reflection attributes in different types of marine substrate (rock, shallow gas, sediments) using seafloor samples for ground-truth statistical comparisons. The data analyzed include seismic reflection profiles collected using two CHIRP subbottom profilers (Edgetech Model 3100 SB-216S), with frequency ranging between 2 and 16 kHz, and a number (38) of sediment samples collected from the seafloor. The statistical method used to discriminate between different substratum responses was the non-parametric Kruskal-Wallis analysis, carried out in two steps: 1) comparison of Seismic Attributes between different marine substrates (unconsolidated sediments, rock and shallow gas); 2) comparison of Seismic Attributes between different sediment classes in seafloors characterized by unconsolidated sediments (subdivided according to sorting). These analyses suggest that amplitude-related attributes were effective in discriminating between sediment and gassy/rocky substratum, but did not differentiate between rocks and shallow gas. On the other hand, the Instantaneous Frequency attribute was effective in differentiating sediments, rocks and shallow gas, with sediment showing higher frequency range, rock an intermediate range, and shallow gas the lowest response. Regarding grain-size classes and sorting, statistical analysis discriminated between two distinct groups of samples, the SVFS (silt and very fine sand) and the SFMC (fine, medium and coarse sand) groups. Using a Spearman coefficient, it was found that the Instantaneous Amplitude was more efficient in distinguishing between the two groups. None of the attributes was able to distinguish between the closest grain size classes such as those of silt and very fine sand.

scholarly journals High-resolution, shallow, seismic reflection surveys of the Northwest Reelfoot Rift boundary near Marston, Missouri

1995 ◽  
Author(s):  
J.K. Odum ◽  
E.A. Luzietti ◽  
W.J. Stephenson ◽  
K.M. Shedlock ◽  
J.A. Michael
Keyword(s):  
High Resolution ◽  
Seismic Reflection ◽  
Shallow Seismic

scholarly journals Optimum offset shallow seismic reflection software

1984 ◽  
Author(s):  
E J Normington ◽  
S E Pullan
Keyword(s):  
Seismic Reflection ◽  
Shallow Seismic
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