Well productivity index
Productivity index from a stabilized rate and flowing bottomhole pressure, the drawdown, and the rate at another bottomhole pressure (straight-line IPR).
J = q / (P_res − P_wf)q₂ = J · (P_res − P_wf2)The straight-line IPR holds for single-phase inflow — while the bottomhole pressure is above the bubble point; below it the productivity falls (see Vogel's IPR). Both pressures at the same depth and on the same scale (absolute or gauge).
Source: Economides M.J. et al., Petroleum Production Systems, ch. 2 (undersaturated oil inflow)
Inputs
You can change a field's unit: the value is converted to the formula's units automatically.
The liquid rate gives J for liquid, the oil rate J for oil. Measure after the well has stabilized.
From the latest shut-in survey (build-up), referred to the mid-perforation depth.
A downhole gauge, or calculated from the fluid level — at the same depth as the reservoir pressure.
E.g. after a pump or choke change; for a straight line it should not fall below the bubble point.
Unit converter for this formulaLiquid rate · Pressure · Productivity index
- m³/d1
- m³/h0.0416667
- L/s0.0115741
- L/min0.694444
- m³/min0.000694444
- bbl/d6.28981
- Mbbl/d0.00628981
- ft³/d35.3147
- US gpm0.183453
- bbl/min0.00436792
A day is 24 hours.
- ΔP — Drawdown–
- q₂ — Rate at the new bottomhole pressure–
More in Inflow and productivity
Oil rate at any bottomhole pressure and the absolute open flow (AOF) from one test: a straight line above the bubble point, Vogel's curve below it. For a saturated reservoir (P_b ≥ P_res) it is Vogel's curve alone.
Flowing bottomhole pressure and pump intake pressure of a rod-pumped or ESP well from the casing pressure and the annular fluid level: oil in the annulus above the pump intake, the produced mixture below it.
Results are engineering estimates from standard formulas; for design decisions check them against the codes, project documents and specialists' calculations. The formulas carried over from the original set are unchanged, and their errors are described in the notes.