fmuobs doesn't handle ERT observation ERROR_MODE

[alifbe]

fmuobs doesn't process ERROR_MODE keyword in ERT observation file and assume it's always ABS This causes issue when user input file is using relative error mode

[alifbe]

As first step, give a warning when user is using relative error mode.

[alifbe]

Some ideas from @rnyb

• Dump both relative error and absolute error when exporting to ResInsight CSV file --> check if ResInsight is strict with file structure
• Check if webviz is reading error mode

[asnyv]

regarding webviz:
webviz-subsurface uses the observation format as defined in fmu-ensemble: https://github.com/equinor/fmu-ensemble/blob/master/src/fmu/ensemble/observations.py
so no relative error there.

I wasn't even aware of the existence of ERROR_MODE, but from the documentation the ERROR_MODE is only mentioned for observations of type HISTORY_OBSERVATION which aren't supported in neither ResInsight or Webviz as far as I know. So in that case they could probably just be dropped?
Do you know if it is valid to use other ERROR_MODE for SUMMARY_OBSERVATION too? If that is the case I guess the best is to calculate the abs error based on the mode and the value to export as an abs value to yml (webviz/fmu-ensemble) and resinsight formats?

[alifbe]

@asnyv from what I can see in ERT code, ERROR_MODE is supported for both HISTORY_OBSERVATION and SUMMARY_OBSERVATION

https://github.com/equinor/ert/blob/b89d49d3dc84e49fb03a05e8042d0c9636db9c6f/src/ert/config/observations.py#L294
https://github.com/equinor/ert/blob/b89d49d3dc84e49fb03a05e8042d0c9636db9c6f/tests/unit_tests/config/parsing/test_observations_parser.py#L152
https://github.com/equinor/ert/blob/b89d49d3dc84e49fb03a05e8042d0c9636db9c6f/tests/unit_tests/config/observations_generator.py#L80

Since webviz always assume absolute error, this will make it easier. fmuobs can, as you suggested, report absolute error when converting to both resinsight and yml format.

[rnyb]

Created an issue here: equinor/ert#7132