Wellbore Inflow Performance (Vogel IPR) Calculator

Generate non-linear Inflow Performance Relationship (IPR) curves and calculate maximum open-flow potential (q_max) for saturated solution-gas drive reservoirs.

Reservoir & Test Well Data

Average Reservoir Pressure P_R (bar):

Bubble Point Pressure P_b (bar): Saturated reservoir if P_R ≤ P_b

Test Oil Flow Rate q_test (STB/day):

Test Flowing BHP P_wf,test (bar):

Target Operating BHP P_wf (bar):

Inflow Performance Deliverability

Max Potential Rate (q_max / AOF):

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Rate at Target BHP:

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Productivity Index (PI at P_R):

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Drawdown at Target (P_R - P_wf):

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Well Inflow Operating Status:

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Frequently Asked Questions

What is Vogel’s Inflow Performance Relationship (IPR)?

Published by J.V. Vogel in 1968, the empirical equation q/q_max = 1 - 0.2(Pwf/PR) - 0.8(Pwf/PR)² describes well inflow when reservoir pressure is below bubble point, accounting for relative permeability loss as free gas boils out of solution.

Why does the IPR curve bend downwards at lower flowing bottomhole pressures?

As pressure drops, solution gas expands into free gas bubbles that block oil flow channels (gas saturation increases, drastically dropping oil relative permeability kro) and oil viscosity rises.

What is Absolute Open Flow (AOF or q_max)?

AOF is the theoretical maximum production rate a well could deliver if bottomhole flowing pressure Pwf could be drawn down completely to absolute zero (atmospheric pressure).