hey, how could i calculate drainage volume by pressure transient analysis?
please check the steps those I think....

1) calculate effective permeability(k) from pressure transient analysis using Fekete soft.
2) calculate radius of investigation r(inv).
3) estimate drainage volume V = Ah = 3.1416*r(inv)*r(inv)*h

where, A = drainage area; h = reservoir thickness.

Now please tell me whether this procedure is correct or not. I am eagerly waiting for your replies.