Difference between revisions of "Productivity index"

Revision as of 10:34, 14 June 2023

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

J is defined as follows:

{J} = \frac{q}{\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}}

Thus, rate could be calculated as:

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

B

= formation volume factor, bbl/stb

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

\mu

= viscosity, cp

@@ Line 11: / Line 11: @@
 Thus, rate could be calculated as:
 :<math> {q} = {J}(\bar{P} - P_{wf})</math>
-==Maximum <math>J_D</math>==
-The maximum possible stimulated well potential for pseudo steady linear flow is:
-<math>{J_D}_{max}= \frac{6}{\pi} \approx 1.91 </math> , see [[6/π stimulated well potential]]
-The maximum possible stimulated well potential for steady state linear flow is:
-<math>{J_D}_{max}= \frac{4}{\pi} \approx 1.27 </math> , see [[4/π stimulated well potential]]
 == Nomenclature  ==
@@ Line 27: / Line 17: @@
 :<math> kh</math> = permeability times thickness, md*ft
 :<math> \bar{P} </math> = average reservoir pressure, psia
-:<math> P_{\bar{P}} </math> = average reservoir pseudopressure, psia<sup>2</sup>/cP
 :<math> P_{wf} </math> = well flowing pressure, psia
-:<math> P_{P_{wf}} </math> = average well flowing pseudopressure, psia<sup>2</sup>/cP
 :<math> q </math> = flowing rate, stb/d
-:<math> q_g </math> = gas rate, MMscfd
 :<math> r_w </math> = wellbore radius, ft
 :<math> r_e </math> = drainage radius, ft
 :<math> S </math> = skin factor, dimensionless
-:<math> T </math> = temperature, °R
 ===Greek symbols===