Productivity index

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J - well productivity index characterizes how much oil or water a well can produce per unit of the pressure drop.

Math & Physics

J is defined as follows:

 {J} = \frac{q}{\bar{P} - P_{wf}}

Thus, rate could be calculated as:

 {q} = {J}(\bar{P} - P_{wf})

From the Darcy's law for an unfractured well located in the center of a circular drainage area, the J in pseudo-steady state is:

 {J} = \frac{kh}{141.2 B \mu} {J_D} = \frac{kh}{141.2 B \mu} \times \frac{1}{ln{\frac{r_e}{r_w}-\frac{3}{4}+S}}


 B = formation volume factor, bbl/stb
 J = productivity index, stb/psia
 J_D = dimensionless productivity index, dimensionless
 kh = permeability times thickness, md*ft
 \bar{P} = average reservoir pressure, psia
 P_{wf} = well flowing pressure, psia
 q = flowing rate, stb/d
 r_w = wellbore radius, ft
 r_e = drainage radius, ft
 S = skin factor, dimensionless

Greek symbols

 \mu = viscosity, cp

See Also