A vibroseis reflection seismic survey at the Buchans Mine in central Newfoundland

Geophysics ◽  
1993 ◽  
Vol 58 (1) ◽  
pp. 154-166 ◽  
Author(s):  
Carl Spencer ◽  
Geoffrey Thurlow ◽  
James Wright ◽  
Don White ◽  
Peter Carroll ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Massive Sulfide ◽  
Careful Analysis ◽  
Fault Zones ◽  
Geophysical Data ◽  
Seismic Survey ◽  
Signal To Noise ◽  
Reflection Seismic ◽  
Seismic Sections

We present results from the first major vibroseis seismic reflection survey at a mine site in North America. It is demonstrated that conventional high‐stack fold reflection seismic techniques can image fault structures associated with volcanogenic massive sulfide bodies, despite the fact that these structures are locally steeply dipping and produce records with low signal‐to‐noise ratios. The new lines were recorded at the locations of two earlier experimental explosive surveys that failed to image many strong reflectors. The principal reasons for the success of the vibroseis experiment were the proper choice of sweep frequencies for maximum signal‐to‐noise ratio, the use of high‐stack fold, and the careful analysis of velocities and statics during processing. A comparison of the new seismic sections with borehole and other geophysical data indicates that the origin of reflections at Buchans can be attributed to various mechanisms including contrasts in lithologies and rock competence and intrusion of diabase sills into pre‐existing fault zones. The best reflections emanate from shallow‐dipping brittle‐ductile thrust fault zones characterized by fault gouge within broader fractured zones. The two seismic lines presented have proven to be a useful and cost‐effective supplement to existing borehole and geophysical data and have provided enough new information on the nature of thrust faulting at the mine to significantly influence current exploration plans.

Geophysics in the new millennium

Geophysics ◽  
2001 ◽  
Vol 66 (1) ◽  
pp. 14-14
Author(s):  
Larry Lines ◽  
John P. Castagna ◽  
Sven Treitel
Keyword(s):  
Signal To Noise Ratio ◽  
Geophysical Methods ◽  
Cost Effective ◽  
Geophysical Data ◽  
First Century ◽  
Writing Quality ◽  
Signal To Noise ◽  
Effective Implementation ◽  
Earth Models ◽  
Noise Ratio

Upon entering the twenty‐first century, we see wide‐ranging changes in geophysics. As of this writing, quality and utility of geophysical data continues a trend of inexorable improvement punctuated by individual quantum steps (such as the 3-D seismic revolution). To a large extent, this improvement has been accomplished on the coattails of advances in computing and related disciplines. These advances have allowed cost‐effective implementation of methods that exploit our steadily increasing understanding of geophysical theory in ever increasingly realistic earth models. As a result, geophysical methods can now provide clearer images at greater distances with bette resolution and signal‐to‐noise ratio than ever before.

A comparison of data from airborne, semi‐airborne, and ground electromagnetic systems

Geophysics ◽  
2001 ◽  
Vol 66 (5) ◽  
pp. 1379-1385 ◽  
Author(s):  
Richard S. Smith ◽  
A. Peter Annan ◽  
Patrick D. McGowan
Keyword(s):  
Signal To Noise Ratio ◽  
Digital Processing ◽  
Test Site ◽  
Massive Sulfide ◽  
Late Time ◽  
Signal To Noise ◽  
Waveform Data ◽  
Ground Survey ◽  
Ground System ◽  
Noise Ratio

The region around a small conductive massive sulfide body near Sudbury, Ontario, Canada, was used as a test site to compare airborne and ground electromagnetic (EM) systems with a new experimental EM system that uses a ground‐based transmitter and an airborne receiver. In this test survey, the semi‐airborne data were acquired with the transmitter loop used for the ground survey and the receiver normally used for the airborne system. At the time the data were acquired, there was no synchronization between the semi‐airborne receiver and the ground transmitter. However, subsequent digital processing of the full waveform data allowed the zero‐time position to be defined. The data could then be stacked and windowed. The ratio of the peak signal to the late‐time noise level for the airborne data is about 25:1, the semi‐airborne data shows signal‐to‐noise ratios of 500:1, while the signal‐to‐noise ratio for the ground data has a ratio of 50 000:1. This particular conductor is very close to the ground transmitter and receiver, so the signal‐to‐noise ratio for the ground system is very high. Numerical modeling shows that the marked advantage of the ground system is reduced when the conductor is deeper. However, the semi‐airborne system will generally show signal‐to‐noise intermediate between the airborne and ground systems. From an operational perspective, the semi‐airborne system has features of both the ground and airborne systems. Like the ground system, it is necessary to lay a transmitter loop on the ground; but because an aircraft is used, the semi‐airborne receiver can cover the survey area much more quickly.

SOME TECHNICAL ASPECTS OF REFLECTION SEISMIC PROSPECTING IN THE SAHARA

Geophysics ◽  
1958 ◽  
Vol 23 (3) ◽  
pp. 557-573 ◽  
Author(s):  
M. Pieuchot ◽  
H. Richard
Keyword(s):  
Seismic Reflection ◽  
Signal To Noise Ratio ◽  
Small Signal ◽  
Signal To Noise ◽  
Low Frequencies ◽  
Technical Aspects ◽  
Reflection Seismic ◽  
Linear Dimensions ◽  
Single Trace ◽  
Selection Of

The small signal‐to‐noise ratio encountered in the Sahara required the development of special techniques. The gentle dips and low frequencies permitted the use of a pattern of 100 shot holes recorded by an array of 100 or more geophones per trace with the linear dimensions of the arrays of the order of 100 m. The large structural dimensions allowed the compositing of as many as 5 records into a single trace. Seismic reflection exploration was made economically feasible by the use of pneumatic hammers for drilling and the less expensive nitrates for explosives. The experimental procedures leading to the selection of the techniques are described.

Northwestern Williston Basin case histories with 3-D seismic data

Geophysics ◽  
1991 ◽  
Vol 56 (11) ◽  
pp. 1849-1874
Author(s):  
D. L. Connelly ◽  
B. J. Ferris ◽  
L. D. Trembly
Keyword(s):  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Cost Effective ◽  
Field Studies ◽  
Careful Analysis ◽  
Williston Basin ◽  
Event Correlation ◽  
Near Surface ◽  
Single Fold ◽  
Exploration Area

Two Northwestern Williston Basin field studies illustrate the cost‐effective geological and three‐dimensional seismic methods used to explore for structurally controlled oil reservoirs in the Tule Creek area of northeast Montana. These examples present the geologic and seismic characteristics of a Mississippian Charles C zone pool at Northwest Poplar field and a Devonian Nisku accumulation at Long Creek West field. A classic, upward‐shoaling, nearshore marine carbonate sequence characterizes the reservoir and associated strata in both fields. The Charles C zone pool of Northwest Poplar field is a subtle, tectonically‐controlled accumulation which remained undiscovered and downdip from the large, nearby, well‐known East Poplar field until 1983. Long Creek West field exhibits the subtle character of small closed structures produced by multistage evaporite solution. Three‐dimensional (3-D) seismic techniques best detect such fields of low vertical relief and small areal extent. The significant acquisition costs of multifold, 3-D seismic surveys led us to design, acquire, process, and interpret single‐fold 3-D surveys to disclose these subtle, small structures. Augmented conventional 48-channel vibroseis crews collected the 3-D data. Near‐surface glacial till deposits in the area created residual statics and normal‐moveout problems on the single‐fold data. These processing problems were handled by constraining the statics and normal‐moveout velocity solutions with plausible geologic conditions: the near‐flat attitude of the reflecting beds, and the inferred horizontal simplicity of the earth velocity field. Our geologically constrained processing methods included: single‐event correlation picking, single‐fold, surface‐consistent statics, and velocity interpolation on flattened events. In addition, spatially oriented six‐fold stacking increases the signal‐to‐noise ratio in areas where poor signal quality exists. In the case of Northwest Poplar field, geologic studies and subsequent interpretations involving isochron mapping techniques showed that the absence of Mississippian evaporites and paleostructural thinning produce disruption of evaporite events and interval thinning near the evaporites, respectively. Long Creek West field exhibited the interval thickening below, and the interval thinning above the trap formed by two‐stage evaporite solution. Careful analysis of geologic conditions coupled with single‐fold 3-D methods makes it possible to economically explore for small undiscovered structural traps in a mature exploration area.

Realization of high signal-to-noise ratio offshore seismic survey with interferometric approach

2018 ◽  
Author(s):  
Hiroaki Ozasa ◽  
Eiichi Asakawa ◽  
Fumitoshi Murakami ◽  
Ehsan Jamali Hondori ◽  
Junichi Takekawa ◽  
...  
Keyword(s):  
Signal To Noise Ratio ◽  
Seismic Survey ◽  
High Signal ◽  
Signal To Noise ◽  
Noise Ratio

Real-Time Capacitive Detection of Microdroplets

2010 ◽  
Author(s):  
Caglar Elbuken ◽  
Tomasz Glawdel ◽  
Danny Chan ◽  
Carolyn L. Ren
Keyword(s):  
Real Time ◽  
Silicone Oil ◽  
Signal To Noise Ratio ◽  
Cost Effective ◽  
Passivation Layer ◽  
Experimental Results ◽  
Capacitive Sensors ◽  
Signal To Noise ◽  
Microfabrication Techniques ◽  
Capacitive Detection

This paper presents a cost-effective and scalable method for real-time detection of microdroplets in microchannels. Sensing electrodes are manufactured using standard microfabrication techniques. Commercial capacitive sensors are used for detection. The functional and simple hardware ensures portability and yields a signal-to-noise ratio of 4 for electrodes covered with a passivation layer. Experimental results for detection of aqueous droplets in silicone oil are presented.

scholarly journals Seismic mapping of Lower Tertiary sediments offshore West Greenland between 64° and 68°N

1979 ◽  
Vol 95 ◽  
pp. 50-53
Author(s):  
J.B Risum
Keyword(s):  
Geophysical Data ◽  
Petroleum Exploration ◽  
Geological Survey ◽  
The West ◽  
West Greenland ◽  
Reflection Seismic ◽  
Lower Tertiary ◽  
Seismic Sections

During 1977 and 1978 the first data obtained from commercial petroleum exploration of the West Greenland shelf were released (Henderson, 1978). The release consisted of geophysical data, mainly in the form of reflection seismic sections, and of a summary of information from the Kangamiut 1 well (Geological Survey of Greenland, 1978). This was drilled during 1976 to a total depth of 3874 metres, and allows the geophysical interpretations to be tied into a stratigraphicai framework.

Noise attenuation by Vibroseis whitening (VSW) processing

Geophysics ◽  
1983 ◽  
Vol 48 (5) ◽  
pp. 543-554 ◽  
Author(s):  
Cahit Coruh ◽  
John K. Costain
Keyword(s):  
Coastal Plain ◽  
Signal To Noise Ratio ◽  
Gain Control ◽  
Dominant Frequency ◽  
Atlantic Coastal Plain ◽  
Apparent Velocity ◽  
Signal To Noise ◽  
Reflection Seismic ◽  
Scaling Window ◽  
Atlantic Coastal

Reflection seismic data recorded on the Atlantic Coastal Plain to examine suspected faulting of the shallow (200 m) basement were contaminated by severe ground roll noise with an apparent velocity of 587 m/sec, 25 Hz dominant frequency, and 23 m apparent wavelength. A receiver interval of 5 m and a total spread length of 285 m were used to obtain 24‐fold coverage. Although the noise problem was severe, overlapping source and/or receiver arrays on the surface were not used for the recording geometry in order to avoid a decrease in resolution caused by the smoothing effect of overlapping subsurface coverage. Instead, the large‐amplitude surface waves were attenuated by a process called Vibroseis® whitening (VSW). VSW is based on the application of time‐varying amplitude scaling before Vibroseis crosscorrelation. A conventional method of automatic digital gain control was found to be effective for this purpose. This scaling results in a signal‐to‐noise ratio improvement equal to the gain expected from crosscorrelation. The scaling window length and the length of sweep are the only parameters required to define the signal‐to‐noise improvement for a given swept‐frequency band. A shorter scaling window and longer sweep length give better results because of the higher gain obtained by crosscorrelation. An increase in the quality of Atlantic Coastal Plain data clearly showed that VSW processing resulted in high resolution on stacked sections and made it possible to map shallow basement reflections at 0.2 sec, revealing faults with up to 10 m offset. Reflections from the sedimentary section above basement also became distinct.

scholarly journals Pre and Post-Stack Imaging of 2D Seismic Data Using Time Migration for Ajeel Oil field, Central of Iraq

2019 ◽  
pp. 2186-2195
Author(s):  
Fadhil Abdulabass Obaid ◽  
Ali M. Al-Rahim
Keyword(s):  
Frequency Analysis ◽  
Seismic Data ◽  
Signal To Noise Ratio ◽  
Oil Field ◽  
Seismic Survey ◽  
Signal To Noise ◽  
Final Time ◽  
Time Frequency Analysis ◽  
Time Frequency ◽  
Time Migration

Kirchhoff Time migration was applied in Pre and Post-Stack for 2D seismic survey for line AJ-99N, that is located in Ajeel oilfield in Salah Al-Din Governorate, Central Iraq. The process follows several accurate steps to reach the final time migration stage. The results of applied time migration give an accurate image for the Ajeel anticline reservoir and to improve the signal to noise ratio. Pre-Stack shows a clearer image for the structure in the study area, and the time-frequency analysis insure the result.

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

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