- 387 views
- 321 downloads
Electrical Properties of Rocks
-
- Author / Creator
- Mohammed, Tariq Eamon
-
The electrical conductivity of fluid-saturated porous sediments is influenced by a variety factors such as fractures, texture, and clay content whose behavior, in turn, depends on conditions of saturation, pressure, and temperature. This work attempts to provide new insights on the effect of some of these factors on electrical properties through novel controlled laboratory measurements on natural and artificial sediments; specifically examining three related aspects. First, do pressure-dependent changes in resistivity and velocity correlate with each other and can they be jointly modeled? Second, to what degree does an isolated fracture within an isotropic porous material affect the electrical conductivity anisotropy, and subsequently are such fractures likely to be detectable by electrical measurements in the field? Finally, what factors control the frequency dependent complex conductivity in porous sands containing small amounts of clay? Unique laboratory tests were developed to answer these questions. In the first, the electrical conductivities and ultrasonic wave speeds were measured as functions of confining and pore pressure through two rock samples of differing compressibilities Pressure-dependent variations in velocity and resistivity correlated well in the compressible sample suggesting both data can be jointly used to make inferences on the nature of the porosity in the material. In the second experiment, a new procedure to construct a porous sample containing a single, small aperture fractures was conceived. The electrical anisotropy of these samples was measured revealing that it strongly correlated (r = 0.94) with the relative fracture porosity. However, the samples were only weakly anisotropic (2% to 10%) suggesting that this effect may not readily be detected under actual field conditions. For the third experiment, complex resistivities were measured from 0.01 Hz to 100 Hz on porous mixtures of natural clays and glass beads. The characteristic relaxation times derived from the observed imaginary component correlated strongly with the diameters of the glass beads and were not related to the physical properties of the different clay materials used. This, taken together with the fact that the clay-free glass bead samples displayed no dispersion provides evidence that membrane polarization dominates over Stern-layer polarization.
-
- Subjects / Keywords
-
- Graduation date
- Fall 2019
-
- Type of Item
- Thesis
-
- Degree
- Doctor of Philosophy
-
- License
- Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.