Specifications

University of Pretoria etd – Combrinck, M (2006)
-2.5
-2
-1.5
-1
-0.5
0
0.5
0 50 100 150 200 250 300 350 400 450 500
Depth [m]
Apparent conductivity [S/m]
Input model
SLDT: no depth factor
SLDT: depth factor 1
SLDT: depth factor 2
SLDT: depth factor 3
TEMIX 3L inversion
TEMIX 10L smooth inversion
0.001
0.01
0.1
1
0 50 100 150 200 250 300 350 400 450 500
Depth [m]
Apparent conductivity [S/m]
Input model
SLDT: no depth factor
SLDT: depth factor 1
SLDT: depth factor 2
SLDT: depth factor 3
TEMIX 3L inversion
TEMIX 10L smooth inversion
Figure 4-21: Comparison of S-layer differential transform (SLDT) solutions using different
depth factors and layered earth inversions of synthetic data for a three layer earth (thick
conductive layer). Top: negative values included; Bottom: no negative values.
The thick conductive layer (Model 3) shows an apparent failure of the SLDT algorithm
with decreasing depths calculated at increasing times, resulting in negative apparent
conductivities (Figure 4-21). This is explained by the “reflecting smoke ring” concept
where high conductance features start acting as a secondary source and additional currents
are generated diffusing both upward and downward from this point. However, at some
stage the primary diffusive pattern outlives the secondary event and the expected increase
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