Specifications

University of Pretoria etd – Combrinck, M (2006)
5.4 Conclusions and recommendations
The automated procedures outlined in chapter 4 can be implemented on both ground
and airborne central loop configuration TDEM data. Filters to remove noise
as well as
clean data not conforming to the assumptions made in the S-layer differential transform
can be applied efficiently in the time and spatial domains retaining the main advantage of
the transform compared to inversion algorithms, namely speed. A combination of decay
curve analysis and the S-layer differential transform allows sensitivity to both high
conductivity contrast (well defined by exponential decay) and low contrast models (well
defined by the S-layer transform). Care has to be taken when interpreting conductivity
depth images, especially in the case of non-horizontal and especially near-vertical
conductors as these will cause migration effects similar to that found in seismic sections.
The procedures outlined in this work are considered to be completely automated since no
starting model or information other than survey configuration and parameters are
needed. Although the automated product is not considered to be a final interpretation it
does provide very useful first phase identification of the subsurface conductivity.
Recommendations for further work are to:
• develop conductivity-depth section migration algorithms to correct for these
effects
• test the effectiveness of the noise and SDTC filters on the more generalised
inversion procedure described by Tartaras et. al. (2000)
• have borehole or other geological feedback in order to quantify the accuracy of
the conductivity depth sections
• implement these, or similar algorithms, in TDEM instruments (such as a new
generation metal detector) with the potential of real time imaging of data.
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