scholarly journals Single-hole short-pulse borehole radar experiments and a crosshole transponder

1986 ◽  
Author(s):  
D L Wright ◽  
R D Watts ◽  
E Bramsoe
Keyword(s):  
Short Pulse ◽  
Single Hole ◽  
Borehole Radar

Borehole radar applied to characterization of fracture zones

1989 ◽  
Vol 20 (2) ◽  
pp. 149 ◽  
Author(s):  
O. Olsson ◽  
L. Falk ◽  
O. Forslund ◽  
B. Niva ◽  
E. Sandberg
Keyword(s):  
Granitic Rock ◽  
Short Pulse ◽  
3D Models ◽  
Radar System ◽  
Fracture Zones ◽  
Borehole Logging ◽  
Single Hole ◽  
Pulse Radar ◽  
Borehole Radar

A new short-pulse radar system (RAMAC) developed by ABEM AB has now been in operation for three years during which more than 100 km of borehole logging has been performed. The bulk of the surveys have been in granites and gneisses.The RAMAC system operates at centre frequencies in the interval 20 to 60 MHz. At those frequencies single-hole reflection ranges of 50 to 150 m are normally obtained in gneissic and granitic rock. Cross-hole ranges have in some cases exceeded 300 m. The large probing range in combination with resolution of the order of a few metres makes borehole radar a unique technique for investigation of fracture zones in crystalline rock.Case histories illustrate application of the RAMAC system in three different configurations (single-hole reflection, cross-hole reflection, and cross-hole tomography) and demonstrate how combination of these three can yield consistent 3D models of fracture zones and other structures.

$\hbox{HE}_{11}$ Mode Effect on Direct Wave in Single-Hole Borehole Radar

2011 ◽  
Vol 49 (2) ◽  
pp. 854-867 ◽  
Author(s):  
Satoshi Ebihara ◽  
Akihito Sasakura ◽  
Taro Takemoto
Keyword(s):  
Direct Wave ◽  
Single Hole ◽  
Mode Effect ◽  
Borehole Radar

scholarly journals Permittivity Measurement Using Borehole Radar from Single Hole

2004 ◽  
Author(s):  
S. Lin ◽  
Y. Sanada ◽  
T. Matsuoka ◽  
Y. Ashida
Keyword(s):  
Permittivity Measurement ◽  
Single Hole ◽  
Borehole Radar

Estimation of the penetration angle of a man-made tunnel using time of arrival measured by short-pulse cross-borehole radar

Geophysics ◽  
2010 ◽  
Vol 75 (3) ◽  
pp. J11-J18 ◽  
Author(s):  
Sang-Wook Kim ◽  
Se-Yun Kim ◽  
Sangwook Nam
Keyword(s):  
Arrival Time ◽  
Short Pulse ◽  
Test Site ◽  
Radar System ◽  
Time Of Arrival ◽  
Arrival Times ◽  
Borehole Radar ◽  
Deep Underground ◽  
Electromagnetic Signals ◽  
Amplitude Level

The relatively fast propagation of electromagnetic signals through empty man-made tunnels has played a key role in detecting deep underground tunnels using a short-pulse cross-borehole radar system. Our cross-borehole radar system measured the pulse signatures of an obliquely penetrating tunnel using eight different borehole pairs at a test site in Korea. Compared to the arrival times of the first peaks, the arrival times of the first received signals at an appropriate amplitude level provided an increasingly clear indication of the empty tunnel as its penetration angle became more oblique. A quadratic relationship between the arrival time of the first received signal and the oblique angle of the empty tunnel was obtained in pure granite.

scholarly journals Radio tomography and borehole radar delineation of the McConnell nickel sulfide deposit, Sudbury, Ontario, Canada

Geophysics ◽  
2000 ◽  
Vol 65 (6) ◽  
pp. 1920-1930 ◽  
Author(s):  
Peter K. Fullagar ◽  
Dean W. Livelybrooks ◽  
Ping Zhang ◽  
Andrew J. Calvert ◽  
Yiren Wu
Keyword(s):  
Host Rock ◽  
High Frequency ◽  
Hanging Wall ◽  
Massive Sulfide ◽  
Sulfide Deposit ◽  
Radio Tomography ◽  
Single Hole ◽  
Dipole System ◽  
Rock Heterogeneity ◽  
Borehole Radar

In an effort to reduce costs and increase revenues at mines, there is a strong incentive to develop high‐resolution techniques both for near‐mine exploration and for delineation of known orebodies. To investigate the potential of high‐frequency EM techniques for exploration and delineation of massive sulfide orebodies, radio frequency electromagnetic (RFEM) and ground‐penetrating radar (GPR) surveys were conducted in boreholes through the McConnell massive nickel‐copper sulfide body near Sudbury, Ontario, from 1993–1996. Crosshole RFEM data were acquired with a JW-4 electric dipole system between two boreholes on section 2720W. Ten frequencies between 0.5 and 5.0 MHz were recorded. Radio signals propagated through the Sudbury Breccia over ranges of at least 150 m at all frequencies. The resulting radio absorption tomogram clearly imaged the McConnell deposit over 110 m downdip. Signal was extinguished when either antenna entered the sulfide body. However, the expected radio shadow did not eventuate when transmitter and receiver were on opposite sides of the deposit. Two‐dimensional modeling suggested that diffraction around the edges of the sulfide body could not account for the observed field amplitudes. It was concluded at the time that the sulfide body is discontinuous; according to modeling, a gap as small as 5 m could have explained the observations. Subsequent investigations by INCO established that pick‐up in the metal‐cored downhole cables was actually responsible for the elevated signal levels. Both single‐hole reflection profiles and crosshole measurements were acquired using RAMAC borehole radar systems, operating at 60 MHz. Detection of radar reflections from the sulfide contact was problematic. One coherent reflection was observed from the hanging‐wall contact in single‐hole reflection mode. This reflection could be traced about 25 m uphole from the contact. In addition to unfavorable survey geometry, factors which may have suppressed reflections included host rock heterogeneity, disseminated sulfides, and contact irregularity. Velocity and absorption tomograms were generated in the Sudbury Breccia host rock from the crosshole radar. Radar velocity was variable, averaging 125 m/μs, while absorption was typically 0.8 dB/m at 60 MHz. Kirchhoff‐style 2-D migration of later arrivals in the crosshole radargrams defined reflective zones that roughly parallel the inferred edge of the sulfide body. The McConnell high‐frequency EM surveys established that radio tomography and simple radio shadowing are potentially valuable for near‐ and in‐mine exploration and orebody delineation in the Sudbury Breccia. The effectiveness of borehole radar in this particular environment is less certain.

scholarly journals Dam Leakage Detection by Borehole Radar: A Case-History Study

2019 ◽  
Vol 11 (8) ◽  
pp. 969 ◽  
Author(s):  
Sixin Liu ◽  
Xudong Wang ◽  
Qi Lu ◽  
Honqing Li ◽  
Yuanxin Wang ◽  
...  
Keyword(s):  
High Resolution ◽  
Internal Erosion ◽  
Leakage Detection ◽  
Low Velocity ◽  
Dam Foundation ◽  
Concrete Walls ◽  
Single Hole ◽  
Reflection Profile ◽  
Borehole Radar ◽  
Water Saturated

A borehole radar investigation was performed at the Sanzuodian reservoir, Chifeng, China to assess possible leakage paths located in the deep dam foundation. The key methodologies used include both single-hole reflection and cross-hole radar tomography, which make a high-resolution identification of the hydraulic connection paths between upstream and downstream sides possible. The leakage paths are characterized by direct wave loss due to high electromagnetic attenuation in the single-hole reflection profile and the nearly horizontal-banded low-velocity zone in the cross-hole velocity tomography due to possible large internal erosion. Meanwhile, some small structures inside the dam, including the core wall thickness changing point, the connecting point between asphalt and concrete walls, and the contacting interface between the dry and the water-saturated formations can be identified from the single-hole reflection profile clearly. Interpreted leakage paths are proven by the water flow measurement. Borehole radar is a useful high-resolution tool, suitable for deep leakage detection and evaluation.

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