WellCAD Basics - Advanced Logic Technology

BOOK 1 - WELLCAD BASICS - 163
The information entered in the Remarks tab will be shown when a model is loaded
into the Spectral Gamma Model Processing dialog box (see 1.5.13.6 Process
Spectral Gamma Data).
When finished click the Save Model button located in the lower right edge of the
Model Properties dialog box. This will save a *.SGM file that can be loaded and
applied using the Process Spectral Gamma Data from Process > Common >
Spectral Gamma.
Creating a model based on calibration spectra
In this type of model you will define a number of energy windows and use the
spectra measured in the enriched zones of a calibration pit and their known
concentration of elements to compute a set of calibration coefficients. These
coefficients will be stored inside the model file. The theory of calibration has already
been covered at the beginning of this chapter.
Each enriched zone is referred to as a Calibration Reference in WellCAD. For a
successful computation of calibration coefficients it is necessary that the number of
energy windows is at least equal to the number of Calibration References used. The
number of elements per Calibration Reference must equal the total number of
Calibration References used in the model. E.g. for a KUT model referring to a
calibration pit with three enriched zones (Calibration References) each of the
Calibration References must contain three elements. The number of energy windows
must be at least three. This model building process has been designed to ensure that
the equation system determined from the users input is always valid.
To create a new model based on calibration spectra:
� Load the Borehole Document (*.WCL) file containing the spectra from the
calibration pit measurement. If you do not have this data set you might
continue with the topic below Creating a model based on count rates.
� From Process > Common > Spectral Gamma choose the Window
Based Model option. The Model Properties dialog will open trying to
reload the last model you worked on.
� Click on the New Model button to start from scratch.
� Enter a Model Name and use the Add button in the Energy Window
section to setup a list of windows from which the count rates will be
extracted. The previous paragraph (Creating a model to output window
count rates) described the steps of entering windows.