Author

Ezeagu

Date of Award

4-2002

Degree Name

Master of Science

Department

Geological and Environmental Sciences

Department

Geosciences

First Advisor

Dr. William A. Sauck

Second Advisor

Dr. Estella Atekwana

Third Advisor

Dr. Daniel Cassidy

Access Setting

Masters Thesis-Open Access

Abstract

The aim of this research is to use electrical resistivity and induced polarization (IP) techniques to image in detail the vertical and lateral distribution of resistivity and chargeability in the subsurface region between two or more boreholes. The method involves installing electrodes mounted on PVC pipes in the boreholes. The distribution of resistivity and chargeability around the boreholes is then calculated. The large number of measurements taken is then inverted to produce tomographs or images showing subsurface distribution of resistivity and chargeability. Four cross-hole measurement arrays (pole-pole, dipole-pole dipole-dipole and pole-dipole) were employed in acquiring tomographic data. The tomographs produced show resistive and conductive zones which may were related to the lithology and moisture content in the subsurface, as well as an image of the extent of invasion by the backfill material used to fill the annular space round the pipes (probes). The induced polarization measurements were not very useful due to the problem of contact potentials. Electrical resistivity tomography can therefore provide a means for high-resolution discrete sampling of a subsurface plane and more adequately define zones in petroleum contaminated aquifers which may relate to geochemical zonation.

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