Is it the current estimation of Productivity index?

[ibtisam01]

Hi,

Please tell me, if the following is the correct estimation of Productivity index or not. I am running simulation in Eclipse. I obtain data of the following Summary Keywords:

1. FPR (Pressure avarage Value in psi)
2. WBHP (Well Bottom hole pressure in psi)
3. FOPR (Field oil Production rate in STB/day)
4. FGPR (Field Gas Production rate in STB/day)

Now, I think PI can be calculated as:

In the case of Gas Production, PI = (FOPR+FGPR)/(FOPR-WBHP)

In the absence of Gas Production , PI = FOPR/(FOPR-WBHP)

Please have a look at these and kindly reply.

Thanks in advance.

[vinomarky]

Think it through - your equation is wrong, but from your error you obviously have not thought it through (either that or a brain-fart while typing)

For starters, consider what is PI.... then what is your equation above?

[ibtisam01]

Yes, I think I have written the wrong equation, now i have tried to modify it. Have a look at it and tell me please.

PI = (FOPR+FWPR)/(FPR-WBHP)

where:

1. FPR (Pressure avarage Value in psi)
2. WBHP (Well Bottom hole pressure in psi)
3. FOPR (Field oil Production rate in STB/day)
4. FWPR (Field water Production rate in STB/day)

in the case of no water production:

PI = (FOPR)/(FPR-WBHP)

Gime me your comments please.

Think it through - your equation is wrong, but from your error you obviously have not thought it through (either that or a brain-fart while typing)

For starters, consider what is PI.... then what is your equation above?

[vinomarky]

Yep - although with no water producing, you could still use PI = (FOPR+FWPR)/(FPR-WBHP)

Strictly, you should use a grid block pressure midway between two wells, or at the natural extent of the model rather than average reservoir pressure, but the difference is normally less than 5%

As far as modelling PI goes though, all you are going to see over time is how the rel perm effects change PI with changing saturation.