Apply variable core shifts to core or core-derived data types

ODM version 3.7 sees the introduction of variable core shifts, allowing for different parts of the core to be shifted by different amounts with respect to the log data. A depth shift is associated to a specific interval within a discreet data type.

Core and core-derived data can now be stored in drillers' depths in the ODM database, as this is the true sample reference depth, and core shifts can applied as necessary. The same can be applied to cuttings-derived data (e.g. biostrat from cuttings).

Shift values are stored in a unique data type, set up as 'point – value', and as a result users have the ability to store multiple interpretations of the shift for a well, each stored in their with their own data type. When the user wants to display core or core-derived data in a wellstick next to logs, they have the option to toggle core shifts on-off for selected data types, forcing ODM to calculate the shifted values on the fly.

If the interpreter decides to change the core shift then they only have to edit one data type, rather than editing all the relevant data types or having to re-import data.

Shift methods

There are 2 methods that can be used to apply shifts:

The 'Last value' option will apply the last shift defined before the current depth in the discrete data set.

For example, if my shift data are (depth / shift)...

100 1.0
200 2.0
300 1.0

Then the Last Value option will apply a shift of +1.0 to all depths between 100 and 200, and then a shift of +2 for depths from 200.

The 'Interpolate between shift values' option will interpolate a suitable shift based on the values in the depth shift data.

Using the above example, ODM would apply a shift of +1.0 at a depth of 100, 1.25 at depth 125, 1.50 at depth 150, etc.

Workflow

The attached document outlines how to go about applying core shifts in ODM.

Below: a screenshot demonstrating the application of the different methods of depth shifts in ODM.

Attachments: