The Dahlonega Test Site: Test Bed For Evaluation Of Shallow Subsurface Geophysical Exploration Techniques

1994 ◽  
Author(s):  
Robert C. Kemerait ◽  
Douglas Baumgardt ◽  
Suzanne Leonard
Keyword(s):  
Test Site ◽  
Test Bed ◽  
Shallow Subsurface ◽  
Geophysical Exploration ◽  
Site Test

scholarly journals Borehole temperature log from the Glasgow Geothermal Energy Research Field Site: a record of past changes to ground surface temperature caused by urban development

2020 ◽  
Vol 56 (2) ◽  
pp. 134-152 ◽  
Author(s):  
Sean M. Watson ◽  
Rob Westaway
Keyword(s):  
Heat Flow ◽  
Urban Development ◽  
Coal Mining ◽  
Industrial Revolution ◽  
Test Site ◽  
Research Field ◽  
Geothermal Heat ◽  
Surface Warming ◽  
Shallow Subsurface ◽  
History Of

As part of the Glasgow Geothermal Energy Research Field Site (GGERFS) project, intended as a test site for mine-water geothermal heat, the GGC-01 borehole was drilled in the Dalmarnock area in the east of the city of Glasgow, starting in November 2018. It was logged in January 2019 to provide a record of subsurface temperature to 197 m depth, in this urban area with a long history of coal mining and industrial development. This borehole temperature record is significantly perturbed away from its natural state, in part because of the ‘permeabilizing’ effect of past nearby coal mining and in part due to surface warming as a result of the combination of anthropogenic climate change and creation of a subsurface urban heat island by local urban development. Our numerical modelling indicates the total surface warming effect as 2.7°C, partitioned as 2.0°C of global warming since the Industrial Revolution and 0.7°C of local UHI development. We cannot resolve the precise combination of local factors that influence the surface warming because uncertainty in the subsurface thermal properties trades against uncertainty in the history of surface warming. However, the background upward heat flow through the shallow subsurface is estimated as only c. 28–33 mW m−2, depending on choice of other model parameters, well below the c. 80 mW m−2 expected in the Glasgow area. We infer that the ‘missing’ geothermal heat flux is entrained by horizontal flow at depth beyond the reach of the shallow GGC-01 borehole. Although the shallow subsurface in the study area is warmer than it would have been before the Industrial Revolution, at greater depths – between c. 90 and >300 m – it is colder, due to the effect of reduced background heat flow. In future the GGERFS project might utilize water from depths of c. 90 m, but the temperature of the groundwater at these depths is maintained largely by the past effect of surface warming, due to climate change and urban development; it is thus a resource that might be ‘mined’ but not sustainably replenished and, being the result of surface warming rather than upward heat flow, arguably should not count as ‘geothermal’ heat in the first place. Our analysis thus indicates that the GGERFS site is a poor choice as a test site for mine-water geothermal heat.Supplementary material: A summary history of coal mining in the study area is available at: https://doi.org/10.6084/m9.figshare.c.4911495.v2

Distributed acoustic sensing for shallow seismic investigations and void detection

Geophysics ◽  
2021 ◽  
pp. 1-69
Author(s):  
Yarin Abukrat ◽  
Moshe Reshef
Keyword(s):  
Vertical Component ◽  
Test Site ◽  
Wave Mode ◽  
Invasive Technique ◽  
S Wave ◽  
Near Surface ◽  
Acoustic Sensing ◽  
Shallow Subsurface ◽  
Diffraction Imaging ◽  
Distributed Acoustic Sensing

During the last decade, fiber-optic-based distributed acoustic sensing (DAS) has emerged as an affordable, easy-to-deploy, reliable, and non-invasive technique for high-resolution seismic sensing. We show that fiber deployments dedicated to near-surface seismic applications, commonly employed for the detection and localization of voids, can be used effectively with conventional processing techniques. We tested a variety of small-size sources in different geological environments. These sources, operated on and below the surface, were recorded by horizontal and vertical DAS arrays. Results and comparisons to data acquired by vertical-component geophones demonstrate that DAS may be sufficient for acquiring near-surface seismic data. Furthermore, we tried to address the issue of directional sensing by DAS arrays and use it to solve the problem of wave-mode separation. Records acquired by a unique acquisition setup suggest that one can use the nature of DAS systems as uniaxial strainmeters to record separated wave modes. Lastly, we applied two seismic methods on DAS data acquired at a test site: multi-channel analysis of surface waves (MASW) and shallow diffraction imaging. These methods allowed us to determine the feasibility of using DAS systems for imaging shallow subsurface voids. MASW was used to uncover anomalies in S-wave velocity, whereas shallow diffraction imaging was applied to identify the location of the void. Results obtained illustrate that by using these methods we are able to accurately detect the true location of the void.

Constructing a geophysical test site for a coastal community's research and education activities

2021 ◽  
Vol 40 (3) ◽  
pp. 208-215
Author(s):  
Mohamed Ahmed ◽  
Ryan Turner ◽  
Michael Haley ◽  
Samantha Shyrigh ◽  
Dionel Colmenero ◽  
...  
Keyword(s):  
Research Training ◽  
Real Life ◽  
Test Site ◽  
Site Location ◽  
Geophysical Research ◽  
Shallow Subsurface ◽  
Steel Pipes ◽  
Corpus Christi ◽  
Steel Drums ◽  
Research And Education

A geophysical test site (GTS) contains subsurface targets of known materials, orientations, and depths. GTSs offer unique opportunities for geophysical research, training, and educational activities. They provide platforms to investigate the penetration and resolution of different geophysical techniques for characterizing the shallow subsurface. GTS-based field exercises represent an interesting, motivating, rewarding, and enjoyable experience for students and instructors. We have constructed a GTS at Texas A&M University-Corpus Christi that contains several objects (e.g., steel drums, plastic drums, plastic buckets, steel pipes, and well covers) buried at depths ranging from 0.5 to 3 m to simulate real-life situations. In this article, we provide a thorough description of the site location, subsurface geology, surface topography, and construction methodology, as well as the types, locations, orientations, and depths of the subsurface targets. Research and education significance and implications of the GTS are also described. This article could serve as a reference for the construction of new GTSs worldwide.

Electrical resistivity imaging for long-term autonomous monitoring of hydrocarbon degradation: Lessons from the Deepwater Horizon oil spill

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. B1-B11 ◽  
Author(s):  
Jeffrey Heenan ◽  
Lee D. Slater ◽  
Dimitrios Ntarlagiannis ◽  
Estella A. Atekwana ◽  
Babu Z. Fathepure ◽  
...  
Keyword(s):  
Oil Spill ◽  
Oil Spills ◽  
Test Site ◽  
Deepwater Horizon ◽  
Hydrocarbon Degradation ◽  
Shallow Subsurface ◽  
Beach Sediments ◽  
Resistivity Variation ◽  
Degradation Activity

Conceptual models for the geophysical responses associated with hydrocarbon degradation suggest that the long-term evolution of an oil plume will result in a more conductive anomaly than the initial contamination. In response to the Deepwater Horizon (DH) oil spill into the Gulf of Mexico in 2010, an autonomous resistivity monitoring system was deployed on Grand Terre, Louisiana, in an attempt to monitor natural degradation processes in hydrocarbon-impacted beach sediments of this island. A 48-electrode surface array with a 0.5-m spacing was installed to obtain twice-daily images of the resistivity structure of the shallow subsurface impacted by oil. Over the course of approximately 18 months, we observed a progressive decrease in the resistivity of the DH spill-impacted region. Detailed analysis of pixel/point resistivity variation within the imaged area showed that long-term decreases in resistivity were largely associated with the DH-impacted sediments. A microbial diversity survey revealed the presence of hydrocarbon-degrading organisms throughout the test site. However, hydrocarbon degradation activity was much higher in the DH-impacted locations compared to nonimpacted locations, suggesting the presence of active hydrocarbon degraders, supporting biodegradation processes. The results of this long-term monitoring experiment suggested that resistivity might be used to noninvasively monitor the long-term degradation of crude oil spills.

scholarly journals System Development Test Program for the WR-21 Intercooled Recuperated (ICR) Gas Turbine Engine System

1994 ◽  
Author(s):  
William J. Hawkins ◽  
Douglas Mathieson ◽  
Chris J. Bruce ◽  
Paul Socoloski
Keyword(s):  
Gas Turbine ◽  
System Development ◽  
Test Site ◽  
The United States ◽  
Gas Turbine Engine ◽  
Test Bed ◽  
Site Location ◽  
Test Program ◽  
Turbine Engine ◽  
Engine System

Westinghouse Electric Corporation has teamed with Rolls-Royce to develop an affordable, commercially based Intercooled/Recuperated Gas Turbine Engine System (ICR) for the United States Navy. This engine system known as WR-21 will become the next prime mover on Navy new construction surface combatants. The system development test program for the WR-21 engine system will be carried out at two test sites in geographically different locations. These are the US Navy’s Test Site at the Carderock Division Naval Surface Warfare Center in Philadelphia, Pa. and the Royal Navy’s Admiralty Test House at the Test and Evaluation Establishment, Pyestock in the United Kingdom. This paper will briefly describe the WR-21 engine system with a more detailed discussion of the system development test program itself. This will include descriptions of the system development testing to be performed and the test facilities and data acquisition systems at each test site location. Also discussed are the methods used to establish the required design commonality between each test site to establish test bed cross-calibration and provide test program flexibility and interchangeability of testing at each site.

Miniature array analysis of microtremors

Geophysics ◽  
2013 ◽  
Vol 78 (1) ◽  
pp. KS13-KS23 ◽  
Author(s):  
Ikuo Cho ◽  
Shigeki Senna ◽  
Hiroyuki Fujiwara
Keyword(s):  
Urban Areas ◽  
Rayleigh Waves ◽  
Evaluation Method ◽  
Vertical Component ◽  
Test Site ◽  
Observation Point ◽  
Shallow Subsurface ◽  
Phase Velocities ◽  
Time Required ◽  
Array Analyses

We suggest observing microtremors by using a miniature array consisting of vertical-component seismometers that are placed at the center and on the circumference of a circle with a radius of several tens of centimeters, for identifying the phase velocities of Rayleigh waves with wavelengths exceeding several tens or a hundred meters. We present, as tools for the analysis, a set comprised of the analysis methods for the phase velocity and the evaluation method for the analysis limit, which were recently developed by the authors on the basis of a rigorous theory derived by generalizing a spatial autocorrelation method. We conducted miniature-array observations using four or six servo-type seismometers, JU-215 manufactured by Hakusan Corporation, at about 50 observation points throughout a test site and urban areas in Tsukuba City and its surroundings, which have various topographical and geologic environments. The time required from arrival at an observation point to retrieval averaged about 30 min. We could determine the phase velocities of Rayleigh waves with wavelengths of 40 and 100 m at 91% and 51% of all the observation points, respectively. Miniature array analyses can significantly improve the mobility of observation to infer shallow subsurface velocity structures to the depth of several tens of meters.

Full-resolution 3D GPR imaging

Geophysics ◽  
2005 ◽  
Vol 70 (1) ◽  
pp. K12-K19 ◽  
Author(s):  
Mark Grasmueck ◽  
Ralf Weger ◽  
Heinrich Horstmeyer
Keyword(s):  
Fractured Rock ◽  
Test Site ◽  
Spatial Sampling ◽  
Minimum Requirement ◽  
Shallow Subsurface ◽  
Full Resolution ◽  
Half Wavelength ◽  
Quarter Wavelength ◽  
3D Gpr ◽  
Fractured Limestone

Noninvasive 3D ground-penetrating radar (GPR) imaging with submeter resolution in all directions delineates the internal architecture and processes of the shallow subsurface. Full-resolution imaging requires unaliased recording of reflections and diffractions coupled with 3D migration processing. The GPR practitioner can easily determine necessary acquisition trace spacing on a frequency-wavenumber (f-k) plot of a representative 2D GPR test profile. Quarter-wavelength spatial sampling is a minimum requirement for full-resolution GPR recording. An intensely fractured limestone quarry serves as a test site for a 100-MHz 3D GPR survey with 0.1 m × 0.2 m trace spacing. This example clearly defines the geometry of fractures in four different orientations, including vertical dips to a depth of 20 m. Decimation to commonly used half-wavelength spatial sampling or only 2D migration processing makes most fractures invisible. The extra data-acquisition effort results in image volumes with submeter resolution, both in the vertical and horizontal directions. Such 3D data sets accurately image fractured rock, sedimentary structures, and archeological remains in previously unseen detail. This makes full-resolution 3D GPR imaging a valuable tool for integrated studies of the shallow subsurface.

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