WellCAD Basics - Advanced Logic Technology

90 - BOOK 1 - WELLCAD BASICS
1.4.2.3 RD file import
www.alt.lu
Import Selection:
Place a check mark in front of each channel you would like to import. The channel
chosen to become the master axis of the Borehole Document must be imported and
cannot be unchecked. The ** symbol in the format column indicates the reference
axis that has been selected in the former step of the wizard.
The purpose of the Axis, Import Unit and Reversed axis settings have been
explained in detail above in Single Log Import.
ALT Raw Data files are produced by the ALT Logger data acquisition system and
have the file extension *.RD.
At import time WellCAD needs to rationalize the RD data and extracts only data
according to its needs. WellCAD therefore places some constraints on the import
function with the following two assumptions. WellCAD assumes the same tool for
the entirety of the file and a constant depth based sampling rate. WellCAD takes the
depth of the first record as the start depth and the depth of the last record as the
end depth, and then divides by the number of records minus one, to calculate the
constant sampling rate.
When importing RD files WellCAD will display various messages according to the
task that it is carried out in the Status bar. The stages of importation are:
� WellCAD scans the *.RD file for header information first. If a header
cannot be found and if the option Warn if no header found in the ALT
Logger default settings dialogue box (see below) is checked, a warning
message is displayed. In this case WellCAD will use the default borehole
document header form as specified in the Tools>Options>Header
section.
� WellCAD looks in the RD file for the sampler record (could be more than
one) set in the file by the logging engineer every time he changes the
sampling mode. The sampler record helps to properly reconstruct the
depth data of the file and helps with interpolation if needed. Two situations
are possible: If the sampler is found all is OK. If the sampler is not found,
a warning message will be shown only if Warn if no sample record found
in the ALT Logger default settings dialogue box (see below) is checked. If
this is the case and the file import is continued, WellCAD will assume a
constant depth sample rate and interpolates the depth data as mentioned
previously.
� WellCAD looks in the RD file for the tool configuration file (.TOL file).
The tool configuration file contains all the information relating to the