Impact of conductive minerals on measurements of electrical resistivity
Abstract/Contents
- Abstract
- Rocks which contain conductive minerals can sometimes pass current through the rock matrix. The primary objective of this thesis is to identify the physical rules that govern the effect of conductive minerals on the low frequency electrical properties of rock. This relationship is examined by measuring the complex, frequency dependent resistivity of clean, well characterized artificial sediments in the laboratory. Important factors which mediate the impact of conductive minerals include the volume fraction, the dry conduction fraction and the electrochemistry occurring at the grain/brine interface. The parameters of grain size, porosity, brine salinity and saturation were varied. Conductive grains were substituted for insulating matrix components (up to 30% by volume). Reductions in resistivity were observed at higher frequencies when the conductive fraction was increased. Large and/or abrupt changes were not observed, likely because the dry conductive threshold was not reached. Electrode-brine experiments examined the magnitude of the electrode potential that must be overcome to drive charge transfer across the interfaces between conductive grain and brine. That voltage threshold is relatively high for pyrite compared to the voltage gradients typically present in geophysical measurements so this potential current pathway can often be ignored. Conductive minerals which are present in high enough volumes can form conductive pathways through the host rock. A discussion of ways to predict resistivity in rocks which contain conductive minerals both above and below the dry conduction threshold is included. Below the threshold, the results match those predicted using Archie's law. Above the dry conduction threshold, additional measurements are needed for interpretation.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Tew, Adam Teichert |
|---|---|
| Associated with | Stanford University, Department of Geophysics. |
| Primary advisor | Mavko, Gary, 1949- |
| Thesis advisor | Mavko, Gary, 1949- |
| Thesis advisor | Dunham, Eric |
| Thesis advisor | Dvorkin, Jack, 1953- |
| Advisor | Dunham, Eric |
| Advisor | Dvorkin, Jack, 1953- |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Adam Teichert Tew. |
|---|---|
| Note | Submitted to the Department of Geophysics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Adam Tew
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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