Specifications

University of Pretoria etd – Combrinck, M (2006)
Development of an automated analysis of
TDEM data for the delineation of a finite
conductor in a conductive half space.
by
Magdalena Combrinck
Supervisor: Professor W. J. Botha
Degree: Doctor of Philosophy in Exploration Geophysics
Department: Geology
Abstract
The objective of this work is to find an efficient, preferably automated, algorithm or
interpretational procedure that can be applied in real time to localise conductors buried in
a host rock, with special attention given to a conductor in a conductive environment.
The Time Domain Electromagnetic (TDEM) method is considered and more specifically
the central loop configuration which can be found in both ground an airborne acquisition
systems. The traditional interpretation approach of decay curve analysis is automated and
combined with an adapted S-layer differential transform (Sidorov and Tiskshaev, 1969) to
produce conductivity-depth sections with superimposed decay behaviour at every station.
The adaptations made to the S-layer differential transform include:
• a noise filter to improve performance on field data
• the S-layer differential transform compatibility (SLTC) filter which only allows
data conforming to the basic mathematical assumptions made in the transform to
be processed (This “compatible” behaviour is derived through a number of
synthetic model studies.)
• a depth correction based on the implications of approximating an infinite number
of currents with a single filament.