Frequency Dependence of Electrical Rock Parameters in the VLF Range.
Final rept. 1 Jan 72-30 Jun 75,
INNSBRUCK UNIV (AUSTRIA) ELECTRONICS LAB
Pagination or Media Count:
The effect of induced polarization IP is used to prove electrically at the in situ rock, concentration and grain size of polarizable material in dead rock. For this purpose a sinusoidal alternating current 0.01 Hz to 10 kHz is fed into a Wenner array. The potential difference measured between 13 and 23 of the total distance is compared with the feeding current in amplitude and phase. Exact phase velocity measurements at VLF waves increase the resolution for the measurements of the electric rock parameters by several powers of ten as compared to previous methods. A special type of unsymmetrical small self-resonant helical antenna was designed for measuring the electrical properties of the rock surrounding the borehole from changes in the electrical properties of the helical antenna. The electronic transducer for the determination of the antenna impedance as a function of the frequency is built into the helix. Measuring equipment and applicability are described.
- Geology, Geochemistry and Mineralogy