When setting up a logging schedule for a Fetch instrument using Subsea Array Manager (SAM) software, there is an option in the log event configurator for different sensors/measurements to set ‘progressive logging’ when adding log events. This article describes what this means and when it should be selected.

The progressive logging setting is only necessary when adding a log event for the AZA measurement of a Fetch AZA instrument. The reason it is good practice to select progressive logging when configuring the logging schedule of the AZA measurement is related to pressure drift patterns.

Analysis of many data sets has shown that pressure sensors tend to drift more when new; after a time the rate of drift slows down until they are essentially stable. This is why it is typical to configure a Fetch AZA to make AZA cycles at an initially frequent rate and then slow down progressively until reaching a much slower final rate, i.e. progressive logging.

When selecting progressive logging, there are other settings that need to be inputted to define what that progressive logging schedule looks like. These settings include ‘increase each log’ and ‘maximum log period’.

As a typical example, you may set ‘increase each log’ to 2.00% and ‘maximum log period’ to 28 days. What this means is that the interval between AZA cycles will increase by 2% with each successive cycle until 28 days are reached and thereafter every 28 days.

Progressive logging is not mandatory; if not selected, the AZA cycle will simply take place at fixed intervals. If you are applying short intervals, consider the draw on the battery and how this will affect the overall endurance of the instrument.

You can find out more detail on how to set up a logging schedule for Fetch AZA using SAM by watching the video below.