Relative permeability tables & Endpoint Scaling

[vinomarky]

All,

A few posts of late with questions relating to rel perm table definition in Eclipse has prompted me to take a stab at making this a bit clearer for all.

In the link below you’ll find a spreadsheet I created (v0.1, so may find a few errors!) that will take the typical endpoints and curve parameters to define rel perm tables, and in turn create a set of Eclipse keywords to paste in your deck - Simply select the phases present, enter relevant parameters and the Eclipse keywords and data will be created for you.

This will create static tables to populate in Eclipse, and if all the reservoir attributed to that SATNUM has similar enough properties, then this may be all you need.

If, on the other hand you have SCAL to support saturation/rel perm relationships with (for example) permeability or porosity, then we often want to honour those relationships in your model. By using endpoint scaling we can use the same rel perm curve shape, but stretch it vertically and horizontally to suit each block

How do we do it?

For starters, insert the ENDSCALE keyword in the RUNSPEC section

Then you can calculate all the scaling parameters in software such as Petrel and import them, OR (as I prefer) using the OPERATE keyword to calculate them on the fly. The advantages of calculating at run-time are (1) the scaling applied is readily auditable and remains with the deck and (2) any adjustments made to parameters linked to the scaled parameters (ie Perm mults) automatically result in appropriate scaled parameters being calculated

The most often used (imho) scaling parameters are;
SWL - Connate water saturation
SWCR - Critical water saturation (largest Sw with zero Krw)
SOWCR - Largest oil saturation for which oil is immobile
SGCR - Largest gas saturation for which gas is immobile
KRWR - Krw at residual oil saturation
KRO - Kro at connate water saturation
KRG - Gas rel perm at maximum gas saturation as defined in rel perm table (usually connate water)
KRO - Kr to oil at connate water saturation

The sheet attached has two additional tables in the data input tab - in the first you specify the nI x nJ x nK to apply the endpoint scaling to

The second allows you to specify the parameters you wish to scale, along with the relationship to apply to it - overwrite the variables you wish to scale, select appropriate relationship type and related properties, specify parameters along with (if required) min/max limits to apply and away you go

The default example saved in the sheet is as follows;
- Grid comprising 50 x 45 x 20
- Water/Oil system
- Fitted connate water saturation as a function of permeability: Swir = 0.4031 – 0.0871 x Log(Perm) -- (Limit to Max value of 0.7, min value 0.10)
- Use constant residual oil at 0.2

VM

[link Point to another website Only the registered members can access]

[kader_007]

Great Job!
actually I am working on those issues!
Many Thanks

[reservoir_engineer]

many thanks,
great work brother,

[temr]

Good job

[DAH7542]

Thanks..

[coyee]

Thanks VM

[Avers]

Thanks a lot!

[vinomarky]

Just updated the spreadsheet - fixed a couple minor issues

[bonethug]

A few questions:
-What are a and b?
-What defines a = 0.4031 and b = -0.0871
-What is Pca / Ja?
-What is Pcb / Jb?

Thanks

[osama_libya]

Good Job ; thanks alot

[petengr]

Thanks a lot for this great post!

[yussy]

Thanks