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.

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 Antenna Parts and Waveguide Transmission Line of Short Pulse Radar System Design

2014 ◽  
Vol 14 (12) ◽  
Author(s):  
Maxim Golubtsov ◽  
Vasily Ovechkin ◽  
Natalia Fadeeva ◽  
Alexey Parschikov ◽  
Arkady Borisov
Keyword(s):  
Transmission Line ◽  
System Design ◽  
Short Pulse ◽  
Radar System ◽  
Pulse Radar ◽  
Waveguide Transmission

Investigations of Fracture Zones in Crystalline Rock by Borehole Radar

1985 ◽  
Vol 50 ◽  
Author(s):  
Olle Olsson ◽  
Lars Falk ◽  
Olof Forslund ◽  
Lars Lundmark ◽  
Eric Sandberg
Keyword(s):  
Crystalline Rock ◽  
Pulse Velocity ◽  
Radar System ◽  
Fracture Zones ◽  
Dipole Antennas ◽  
Short Pulses ◽  
Pulse Radar ◽  
Pulse Form ◽  
Position And Orientation ◽  
Very Short Pulses

AbstractA borehole pulse radar system has been developed as part of the International Stripa Project with the objective to identify and characterize fracture zones at a considerable distance from boreholes. The radar uses very short pulses, which are transmitted and received by dipole antennas inserted into the boreholes. The pulses are extremely broadband with center frequencies of 25–60 MHz corresponding to wavelengths of a few meters in the rock. At 25 MHz the attenuation in the Stripa granite is 28 dB/100 m and the pulse velocity is approximately 128 000 km/s. Reflection measurements have been used to identify fracture zones and determine their position and orientation. The zones often cause strong and well-defined reflections. Improvements in the pulse form and numerical filtering of the data have consequently made the radar a very efficient instrument for locating fracture zones. During measurements in Stripa reflections from fracture zones have been observed more than 100 m from the borehole.

BOREHOLE RADAR APPLIED TO THE CHARACTERIZATION OF HYDRAULICALLY CONDUCTIVE FRACTURE ZONES IN CRYSTALLINE ROCK1

1992 ◽  
Vol 40 (2) ◽  
pp. 109-142 ◽  
Author(s):  
OLLE OLSSON ◽  
LARS FALK ◽  
OLOF FORSLUND ◽  
LARS LUNDMARK ◽  
ERIC SANDBERG
Keyword(s):  
Fracture Zones ◽  
Borehole Radar
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