bottom flowing pressure well on delivery

Dear All,

I would like to get an estimate of the bottom flowing pressure in a well that is cross cutting several layers and sometimes several cells in the same layer (when the well is deviated for example).

I tried to use the formulae that are given in p66 of the TOUGH2 manual but I am not sure I fully understand the concept!

If I run the model on deliverability:

If I run the model1 in attachment, which consists of a radial model with 2 layers, how should I calculate the PI? Should it be based on the sum of the thickness of the different layers that the well is cross-cutting or on the top cell thickness. What happens if the layers have different permeabilities? What does the P correspond to in case the well cross-cuts several layers? The pressure in top cell or the pressure at the bottom of the well?

If I run the model setting a given extraction rate such as in model 2: Then I obtain the pressure in the different productive cells but how I calculate back the Pwb?

Thank you in advance for your help. I have been struggling with this issue for too long.

Kind Regards,

Virginie