Specifications
University of Pretoria etd – Combrinck, M (2006)
S-layer transform remains very fast (less than five seconds on a PC for 1500 soundings) no
matter which differentiation method is chosen. Finally, only good quality data can be
expected to give good quality results and if a truly automated process is required a filter
passing only relatively noise-free data should be applied before the S-layer differential
transform is applied
.
4.5 The S-layer correction factor
4.5.1 Defining a S-layer correction factor
The S-layer algorithm applied to the synthetic examples above, necessitated the
implementation of a scale factor in order to obtain the correct depths and conductivity
values. This factor is determined empirically as follows.
Half space responses were calculated using the late time approximation (Kaufman and
Keller, 1983) as well as a numerical implementation of the solution valid for all times (W. J.
Botha, unpublished). The S-layer transform is applied to these voltages in order to obtain
depths and conductivities (resistivities for comparison). These resistivity values are
compared to the original input values. Resistivities used were 10 ohm.m, 50 ohm.m, 100
ohm.m, 500 ohm.m, 1000 ohm.m and 5000 ohm.m with comparative results shown in Fig
4.15. In the figure, the open diamonds are the values obtained from the S-layer transform
applied to the full expression, the filled diamonds those obtained from using the
asymptotic values, while the solid line indicate the original resistivity value.
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