Productivity Index (PI)
Definition - What does Productivity Index (PI) mean?
Productivity Index is the measure of the ability of a well to produce hydrocarbons at a commercial rate. Estimating Productivity Index is one of the necessary and very important steps once the production from an oil or gas well starts. Productivity index tells the operator about the performance of an oil well. It is commonly denoted by “Pi or J”.
Petropedia explains Productivity Index (PI)
Productivity Index is one of the important parameters tested once the well is complete and ready for production. It is the ratio of total flow rate of the liquid to the drawdown pressure and can be written in the form of equation as:
J = Qo / Pr – Pwf = Qo / delta P
J is the Productivity Index in STB/day/Psi
Qo is the flow rate of oil in STB/Day
Pr is the static pressure or volumetric pressure of the average drainage area
Pwf is the bottom hole flow pressure
Delta P = Pr – Pwf = Drawdown Pressure
To measure the Productivity Index of a well, it is shut in until the static reservoir pressure is reached and then it is allowed to produce hydrocarbons at a constant flow rate for a specific amount of time to have a stabilized bottom hole pressure, i.e., to reach pseudo steady state conditions. At pseudo steady state conditions, the Productivity Index can be measured accurately.