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Petrel-ECLIPSE import-export process - Some tips and some classical pitfalls
Recommendation note on Petrel-ECLIPSE
1) Petrel-ECLIPSE grid+properties export 2) Important remarks
3) Petrel property names export rules 4) Default values
5) ECLIPSE-Petrel grid and property import process 6) Petrel/ECLIPSE: importing/exporting faults 7) Quality check: illustration
8) What could go wrong? Some illustrations
1. Petrel-ECLIPSE grid+properties export
You will find a note on the same topic posted on the Intranet and written in French (by Marie-Laure Baratin):
“Procédure de transfert des données du géomodeleur (PETREL/IRAP/GOCAD) vers Eclipse”
There are 2 main manual export options:
1) Export the grid geometry (and possibly some properties together) 2) Export only the grid properties
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We advise you to check that you are using the following settings for the grid AND for the
property export:
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2.Important remarks
In order to improve the communication between geologists and reservoir engineers …
-Geologists:
o you MUST export the grid geometry, the properties and the faults with the SAME settings. We strongly recommend using the “Default ECLIPSE export settings”
mentioned above;
o be aware of the Petrel property names export rules described below;
o be aware that all the exported file names should be in UPPER CASE without
space or special characters (to avoid problems under Unix);
o Quick QC tests (see illustration in last paragraph):
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importing the grid, the faults or the properties back in Petrel will quickly
identify if any has been imported with inconsistent settings or if the property names are indeed those expected by ECLIPSE;
we recommend providing the Reservoir Engineer with a test property (like
a porosity) clearly identifiable, or a check with the Reservoir Engineer the value and indices of a specific cell; only that test will validate the export!!
- Reservoir engineers:
o be aware that some keywords like PINCH, ACTNUM or MAPAXES are by
default present in the exported file (which is not a problem as long as you include the grid geometry first in the ECLIPSE data deck); o Quick QC tests (see illustration in last paragraph):
run ECLIPSE in NOSIM to get the *.EGRID, *.INIT file and *.UNRST
and check that the properties and the grid cell indices in FloViz are consistent with those in Petrel;
How does Petrel select the grid origin?
Petrel takes the decision on where to locate the grid cell origin at the moment it generates the grid. The grid origin location is always (Xmin, Ymax) but Petrel then follows the “right hand side” rule to define in which direction is going to be the I and J axes, so cell (1,1,1) is the closest to the coordinates origin.
What if I want to changes the grid indices for all my filters and for visualization?
Because Petrel and ECLIPSE coordinate systems are different, Petrel provides the flexibility to alter the grid indices to facilitate the comparison. This is available through the Project | Project Settings | Misc settings 2 tab:
This has NO impact on the export results since, internally, Petrel always refers to the default internal Petrel indices and grid cell origin to export. But to preserve consistency, you should always make sure you have the above settings.
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Will the export rules always work, even if my grid is rotated?
Here is a series of grids all generated in Petrel and exported towards ECLIPSE. If you follow the process, then no matter the rotation, your grid+properties will be successfully exported to ECLIPSE/FloViz with the right indices.
Note that we located the default grid origin, the default and swapped cell (1,1) (consistent with FloViz), the I and J axes in Petrel and FloViz for the different angles. We used the ECLIPSE/FloViz swapped J axis (project settings described above).
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In Petrel, the Z axis is pointing upwards (negative depths) and if you consider the default (pink)
cell (1,1) and the internal/original J axis orientation, you will have a “direct” coordinate system
(“right hand side rule”).
In ECLIPSE, the Z axis is pointing downwards (positive depths) and if you consider the swapped
J index (yellow) cell (1,1) and swapped J index orientation, you also get a “direct system”.
So, if you follow the export process with (I=0, J=Jmax, K=0) and always visualize the indices
with the above project settings (Swap J index on), you will always have an axis coordinate
system that respects the “right hand side” rule (“direct” coordinate system) as in ECLIPSE.
3.Petrel property names export rules
Did you ever notice that the names in the exported files were not always quite those that you
expected?
You should be aware that Petrel has some built-in logics around the property templates that
control the exported names:
-For some specific property templates, Petrel automatically exports the ECLIPSE name (independently of the Petrel property name or the template name);
-For some general property templates , Petrel automatically exports the Petrel property name;
-For all the other templates, Petrel automatically exports the Petrel template name;
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If you follow those rules, the Reservoir Engineer will be a lot happier!
Examples:
is exported as “PORO”
is exported as “PHIE”
is exported as “POROSITY-EFFECTIVE”
is exported as “ACTNUM1” if the template is “Region” or “General discrete”
(but could be exported as “ACTNUM”, if you have created a new discrete template that you renamed “ACTNUM”; in this case, it is not a general discrete or region template anymore!)
4. Default property values
Replacing a wrong default value in big files is really a pain for the reservoir engineer. This can be avoided if you discuss first with the reservoir engineer. As a first guess, use the recommended default values listed above for the given property type.
Note that ECLIPSE does not normally accept region numbers that are negative or 0!
In other words, all the region properties should start from 1 for the Reservoir Engineers!!
5. ECLIPSE-Petrel grid geometry and property import process
There are 2 main workflows:
1) Import ECLIPSE keywords (*.GRDECL format): when grid+properties are in GRDECL
format;
2) Import ECLIPSE results (*.EGRID, *.INIT, *.UNRST, …)
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Some important remarks
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Contrary to the “export” process, the “import” process has no control settings, which means that you must be careful when importing as you could run into potential inconsistencies:
- Case 1: you import both EGRID+INIT in Petrel. This is the safest situations since EGRID
and INIT are consistent. No problem here.
- Case 2: you already have your grid geometry in Petrel and you import the INIT. If you have
not followed the export process, then you may get some inconsistent properties as Petrel will revert those properties on import and swap the J axis.
6. Petrel-ECLIPSE: Exporting/Importing Faults
Geologists:
? Be aware that you MUST also keep the SAME export settings as the grid geometry and
properties when you export the faults!
? Be aware that in ECLIPSE, the fault names cannot contain more than 8 characters! ? So please keep track of the Petrel vs ECLIPSE names in the project report and
communicate it to the Reservoir Engineer;
? In Petrel, it is possible to generate a Fault Index using the “Geometrical Modeling”.
You can pass the fault locations with the full names in the project report;
Reservoir Engineers:
?Be aware that you may need to rename the faults!
?When importing the ECLIPSE results in Petrel:
o If you turn on the option, Petrel will analyze grid
discontinuities and identify them as “fault 1”, … They may not correspond to the
ECLIPSE FAULTS keyword at all!
o If you turn off the option, Petrel will not generate faults
and you are now able to convert the ECLIPSE FAULTS keyword (and get the
ECLIPSE fault names in Petrel) as follows:
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7. Quality Check - Illustration
QC for Geologists
- Export the grid, faults, properties from Petrel - Import the grid, faults, properties back in Petrel; - Check the new grid location,
- Check the new property names (to check if they have the correct ECLIPSE name),, - Check a property value and the cell index on a specific grid cell, for example on a test
porosity grid with 2 strikes of porosity = 1 crossing at cell (28,15,1);
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QC for Reservoir Engineers
-Run a NOSIM simulation to get the *.EGRID, *.INIT and *.UNRST files;
-Import them in FloViz and/or Petrel;
-Check a property value and the cell index on a specific grid cell; (for example, the specific cell (28,15,1) has the right value and right indices in FloViz and Schedule) -Check also the position and orientation of the wells compared to the original data in Petrel;
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8. What could go wrong? Some illustrations
Category 1: The imported grid seems totally dislocated but all the properties seem good Answer: investigate if MAPAXES is missing when imported back or if you imported with a global coord system a grid that was exported with a local coord system
Category 2: The grid seems correctly located but the properties are totally strange! Answer: the grid or the properties were exported with different settings.
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Scenario 3: The grid and properties are correctly located, but the faults are totally strange! Answer: the faults were not exported with the same settings as the grid and the properties.
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Scenario 4: The grid and properties are correctly located but the Y axis seems to be inverted in FloViz!!!
Answer: Check that the grid and properties were imported with the recommended settings. Here is what happens when you export the grid geometry+properties with a consistently wrong origin! Also, check that the wells have been recomputed with the same grid in Schedule! In this case, we computed the well locations on the original grid, changed the grid export settings “by mistake” and “forgot” to re-run Schedule: the wells are wrongly located on top of the Y axis inversion problem!