Determination of average drainage area pressure

[pet_spec]

Hello, guys

How the average drainage area pressure could be determined? Is there any simple assumptions or short-cuts ?

I need it to calculate gas compressibility and viscosity?

[06pg22]

Pressure determined from PBU or DD test is Drainage Area Pressure.

Avg Drainage Area Pressure = SQRT((Pwf^2+Pr^2)/2)

[i-anuar]

although well testers hate it, some people use radius of investigation. see attached excel file with formula. but check textbooks regarding pitfalls of this assumption

[dipak_m]

How I calculate of drainage radius of a field. What assumptions we should consider?

[i-anuar]

at some point pressure disturbance will reach boundaries of the field and your well(s) will move from transient to semi steady and steady state flow regimes. i am not sure what you are guys after if it is for the flow rate estimates then drainage radius is not that important as re (external radius) enters logarithm. try to increase re 5-10 times in the Darcy flow equation to test. if you need it for reserves than drainage radius is proportional to $$$ :-) and is important i guess.
is it just me or why and what is needed not clearly explained? ...