Borehole radar system analysis in stratified geological systems applied to imaging of platiniferous reefs in the bushveld igneous
Date
2003-12
Authors
Herselman, Paul Le Roux
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
The imaging of platiniferous reefs in the Bushveld Igneous Complex (BIC) is of great
economical and sociological importance. Borehole radar technology has been
identified as a viable mapping tool to be used in day-to-day mining operations, but a
critical assessment has to be made on the feasibility of this postulation.
The system analysis made of the borehole radar deployed in the BIC is presented in
this dissertation. The analysis is done using a specific example - the GeoMole
borehole radar system.
A novel procedure, based on the basic theory of electromagnetic radiation and
propagation, is proposed by which the entire physical radar system can be
characterized. The power transmitted by an unconventional borehole-deployed
transmitter is estimated by a sequence of free space measurements, numerical
simulations and theoretic derivations and approximations. Antenna transfer functions
(magnitude and phase) are numerically simulated for a variety of deployment
configurations. The total system transfer function of the receiver analogue and digital
chain is determined. This enables the calculation of the radar's performance figures
necessary to determine the applicability of the radar in a specific geological setting.
A radar system is only complete when considered in its environment. The BIC is a
stratified system of numerous rock layers. An in-depth study is done on the
propagation of radiowaves in stratified lossy media. Only the case for non-magnetic
media is discussed in this dissertation. The developed theory is used to predict the
system response to a typical transmitted radar pulse in the UG1 - UG2 stratigraphy of
the BIC, determine the maximum detection range of reef horizons and estimate the
reflectivity of the reefs.
Resolution is one of the key parameters that determine the performance and accuracy
of imaging. An algorithm is proposed, developed and tested by which the resolution
of the system is increased and overlapping echoes become resolvable.
Even though some of the techniques are developed with a specific system in mind, the
applicability of the concepts and algorithms is universal.
Description
Thesis (PhD (Electrical and Electronic Engineering))--University of Stellenbosch, 2003.
Keywords
Theses -- Electrical and electronic engineering, Dissertations -- Electrical and electronic engineering