Rel Perms

[kikiastrid]

Hello Everybody!

As a brand new junior reservoir engineer I am starting with some Eclipse simulations. A really tricky thing is always relative permeability. From what data do I get my basis for relperms implemented in the simulation run. And if I have data, how can I prove that this is the right one (same volume as geological model for example?)?

THX

[vinomarky]

double post - see below

[vinomarky]

Hahahahaha..... sorry... no fault of yours, it's just amusing to read these kinds of posts from fresh engineers. A couple of pointers that I hope will help

1. Geologic model will be wrong
2. Dynamic model will be wrong
3. Our job is to help try to come to the best 'wrong' answer we can, in an appropriate amount of time, and to an appropriate level of uncertainty

Now, rel perms are in themselves a topic that you could spend an entire career studying. Traditionally, they come from SCAL tests (Special Core Analysis), but these tests themselves are affected by the handling/cleaning/testing procedures that we impose, so their validity is suspect from the start. Combine that with the fact that SCAL tests are representative of a very small thickness of rock, and our simulation grid blocks are typically 1m+ thick and you start to get the idea of the sorts of uncertainty we work with here

TYPICALLY, you should seek to determine;
- if the rock is oil/water/intermediate wet
- what the endpoints are (saturation and rel perm)
- What the cap pressure curves look like

Then try to make sure you group similar rock types and perms in each layer, OR use appropriate rel perm pseudoization to reflect the vertical heterogeneities

Anyway, if your head is spinning now, please understand that what I have outlined is actually a simplified answer.....

There are no right answers
Each situation is going to be different
Understand and embrace uncertainty - try to determine extent of it

[jack]

HOW CAN I USE scal DATA (EXCEPT FOR SIMULATOR)WHAT INFORMATION CAN I GET AND HOW TO MAKE DIFFERERENT CHARTS.COULD U THROUGH SOME LIGHT ON IT
REGARDS
jack

[vinomarky]

Lots of stuff - some examples are;

Water compatibility tests - plotting perm to water with pore volumes injected, then doing a back flow to ascertain how much of the degredation is due to fines movement

Capillary pressure test - can get water saturation as a function of permeability and height above free water level

Rel Perm endpoints - an alternate way of inferring critical water saturations

Wettability tests - determine if your formation is water/oil/intermediate wet

The list goes on....

[jack]

thankx a lot.to be frank i am new to SCAL data analysis.if u have some example on how to proceed ,it will be really very helpful.
thanx and regards
jack

[vinomarky]

Not exactly sure what it is you would be after - RCA/SCAL testing really is a subject unto itself, but it is better to think of these tests in terms of answering (or reducing uncertainty in) questions you have.

RCA (regular core analysis) broadly answers questions about the rock fabric - porosity, perm etc.

SCAL (Special core analysis) broadly answers questions about rock/fluid interactions

High levels examples of questions SCAL can help reduce uncertainty in are;
- If you don't believe (or have not calibrated) petrophysically derived saturations, SCAL can help tie down what water saturations you may have
- If you have low perm and/or low relief formations which exhibit significant transitional zone behaviour, SCAL can help characterize your saturations with depth
- If you need to understand how your relative perm will change as saturations change, SCAL can help
- There are a number of uses for calibrating petrophysical logs as well (measuring properties such as resistance that can be related to constants used in their equations) but this is starting to step out of my realm of expertise.

etc....

[jack]

what i would like to know how to use wettability(brine-oil,oil-brine)capiliary pressure,formation resistivity,pore volume compressibilty and relative permeability data.some some charts can be drawn using all these data.pl help
thanx

[vinomarky]

Sorry, but you are asking questions that are entirely too broad without the context of a specific problem you are trying to solve - these are not simple answers

Or to put it in context, imagine if an undergrad was asking you how to use permeability, porosity and pressure... some charts can be drawn using this data. pl help.... where would you start?

[ahmedm]

my friend

you can get the rel perm data from the scal data
plot them vs. water saturation

for the end points you have it too at SWirr and Sor
if you have number of curves you can normalize them
each sample, divide by the end points for oil and water
then plot all samples in one curve then make average curve (make trendline)

from Pc data you can get the Swirr data, plot them vs. logk
then make trnd and also for Sor vs. logk
and for krw0 vs. logk and kro0 vs. log k
so if you have different rock types you can find the end points corresponds to
k, por for each rock type

then you will have number of curves you can assign each for it is rock type


i hope this can help

[jack]

Thank you so much.bless u

[kikiastrid]

It seems that relperms is a hot topic. Thx for your help anyway!