Specifications

University of Pretoria etd – Combrinck, M (2006)

In conclusion, the third scenario for correction correlates best with the actual model depths

on synthetic data and was implemented in the software.

4.5.3 Behaviour of the S-layer transform when applied to synthetic data

In order to test (and develop a better understanding of the method) the conductivity-depth

results of the improved S-layer transform a number of synthetic models are presented with

their corresponding transformed results. Both the cumulative conductance [S] and

conductivity [

σ] curves are given for each model. The influence of noise added to the data

is also investigated. The software used for the forward models is MARCO developed by

AMIRA. The following system parameters were used for modelling:

Receiver area: 1 m

Receiver time channels: 0.08813 ms (Ch. 1) to 6.978 ms (Ch. 20) logarithmically

spaced, i.e. the H range of the Geonics EM37.

Transmitter loop: 50 m X 50 m

Transmitter turn-off time: 40

µs

Transmitter current: 1 A

Configuration: Central loop sounding

4.5.3.1 Half space with conductivity of 0.02 S/m (50 ohm.m)

Figures 4-24 and 4-25 show the results from the S-layer transform for the case of a 50

ohm.m half space. The cumulative conductance curve (Figure 4-24) rises smoothly and the

imaged conductivity versus depth levels out close to the expected value of 0.02 S/m when

the late time approximation as validated.