Saturation height function

[dipak_m]

Dear Temr & Vinomarky,
Thanks. Needs sometime to digest.

[vinomarky]

On reflection, many of you are probably not aware of the different corrections to go from lab measured Pc to Pc (reservoir), so here is a summary below

Pc (Reservoir conditions) = Pc (Lab) x (Sigma.Cos(theta))res / (Sigma.Cos(theta))lab

Typical values of Sigma.Cos(Theta) are;

Lab
Air-Water 72
Oil-Water 42
Air-Mercury 367
Air-oil 24

Reservoir
Water-oil 26
Water-gas 50 (P & T dependent, reasonable value for depth of 5,000ft)

So in my worksheet you'll see that I have calculate reservoir Pc as Lab Pc x 26 / 42, which comes from assumption that your reservoir system is water/oil, and your lab test was water/oil

[dipak_m]

Dear Vinomarky,
How you derived the following equation
Swi = .44/(.00766*(Height*.21)*(SQRT(PERM/PHIT))^.212
Thanks

[vinomarky]

I didn't, was answering swibow's question

[swibow]

Dear Vinomarky,
How you derived the following equation
Swi = .44/(.00766*(Height*.21)*(SQRT(PERM/PHIT))^.212
Thanks

That equation was not from Vinomarky, I got it from our resigned petrophysicist.
And I don't know how he made it, that's why I raised questions on it. But it looks like a J function based sat. height function.

[vinomarky]

Another tidbit -

The topic of upscaling is complex - indeed entire books could be written on it. One of the many pitfalls you can fall into is upscaling a block of net and non-net reservoir togeather.

Scenario:
Two blocks of equal dimensions & pore volume = V, one with 20mD and other with 0.5mD are to be upscaled into one block. You know that anything less than 1mD has (a) no/little charge and (b) no flow contribution, but have not netted it out as the saturation height function takes care of the (lack of) charge properly

Simple averaging of the two blocks would create a single block of 10.25mD and pore volume 2V... It's kh would be more or less correct BUT when you apply your newly created saturation height function to it, you'll probably find you've got around 0.8x2V (or 1.6V or so) of hydrocarbons.... In effect you have added hydrocarbon volume. Additionally for a given flux of (for example) water through the upscaled block, it would take almost twice as long to break through to the other end..... Overall you are creating optimistic HCPV and optimistic breakthrough behaviour

One approach that I have used often to reduce this effect is the following;
1. Create a new perm property as follows PERMX_Cutoff = if(PERMX>1,PERMX,U)
2. Create a NTG property as follows NTG = if(PERMX>1,1,0)
3. Upscale PERMX_Cutoff and NTG

Step 1 sets any perm less than your cutoff (in this case 1mD) as U (undefined in Petrel syntax). In the scenario above, averaging a 20mD and an undefined block togeather would result in 20mD

Upscaling the NTG would result in (1+0)/2 = 0.5

Now, your kh is still preserved, your saturation height function will give you the correct Sw, and the overall volume will be correct

Just some random thoughts that popped to mind this evening....

[hojbarnaz]

dear
vinomarky if you kindly put some light on normalization technique of oil-water and oil-gas relative permeability with some excel exaples at different soi and sor generally used in simulation from special core analysis.it will be helpful for layman like me so that we can able to understand technique of normalization

[vinomarky]

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

[paolomaldini]

thanks for help.

[Aries]

Hi Vinomarky,

I was following the messages in this thread and I tried to download the EXHE.....FUNCTIONS.HTML but it no longer available. Could please have this file available again so that I can follow I can follow all the details? Thanks vinomarky...... aries

[paolomaldini]

Thanks very useful material for bengineers.

[lord_zero82]

Hi Vinomarky,

Where can I find some documentation about this lambda function and the constants? I can't find it anywhere...