Work out oil well production rate instantly with clear inputs, formula shown and shareable results.
Darcy radial inflow for a vertical oil well gives q = 0.00708 k h deltaP / (mu Bo (ln(re/rw) - 0.75)) in stock tank barrels per day, with permeability in millidarcies, thickness in feet and pressure in psi. Productivity index, rate divided by drawdown, is the practical measure of well capability.
Radial inflow equation
q (STB/d) = 0.00708 x k x h x deltaP / (mu x Bo x (ln(re/rw) - 0.75))
Productivity index
PI = q / drawdown
Well inflow performance for reserves reporting or completion design must be established from pressure transient testing and reservoir modelling by qualified petroleum engineers.
Steady-state single-phase radial flow into a vertical well in a homogeneous reservoir, with a 1000 ft drainage radius and 4.25 inch wellbore. Real wells deviate through skin damage, multiphase flow and heterogeneity.
A dimensionless factor added inside the log term representing extra pressure drop near the wellbore from drilling damage or stimulation. Positive skin reduces rate; a successful acid or frac job gives negative skin.