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Nover, G.
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- PublicationOpen AccessThe spectrum of thermally stimulated currents in rock samples from KTB drilling: preliminary results(2001-04)
; ; ; ; ; ;Anastasiadis, C.; Technological Educational Institution of Athens, Greece ;Triantis, D.; Technological Educational Institution of Athens, Greece ;Vallianatos, F.; Technological Educational Institution of Crete, Greece ;Nover, G.; Mineralogisches Institut der Universitat Bonn, Germany ;Nomicos, C.; Technological Educational Institution of Athens, Greece; ; ; ; The technique of thermally stimulated depolarization currents (TSDC) was applied to fine grained amphibolite rock samples extracted from KTB drilling. Each sample was cooled down to liquid nitrogen temperature and consequently heated at a constant rate b = 4 K/min while at the same time it was shorted by a sensitive electrometer. Thermocurrent glow curves were detected in the range from 180 to 360 K. By applying the TSDC method, an effort was made to carry out a preliminary analysis of the TSDC spectrum.163 165 - PublicationOpen AccessThe electrical signature of rock samples exposed to hydrostatic and triaxial pressures(2001-04)
; ; ;Heikamp, H.; Mineralogical Institute, University Bonn, Germany ;Nover, G.; Mineralogical Institute, University Bonn, Germany; The electrical signature of sedimentary (carbonate) and crystalline rock samples was studied in hydrostatic and triaxial pressure experiments up to 300 MPa. The aim was to establish a relation between an electrical signal stimulated by an external pressure acting on the sample and the mechanical stability of the rock. Natural open fractures tend to be closed under hydrostatic pressure conditions, whereas in triaxial pressure experiments new fractures are generated. These contrary processes of either decrease or increase in crack density and geometry, cause a decrease or increase in the inner surface of the sample. Such pressure induced variations in pore geometry were investigated by an interpretation and modelling of the frequency dependence of the complex electrical conductivity. In a series of hydrostatic pressure experiments crack-closure was found in the electrical signature by a decrease of the model capacitor C being related to crack geometry. This capacitor increases in the triaxial experiments where new fractures were formed.111 268