Productivity Index (PI)

Introduction

Productivity index (PI) is an essential element of the oil and gas well performance evaluation package. It is defined as the quantity of oil or gas produced for a certain drop in pressure. It serves as an indication of the deliverability potential of the well. Productivity index is the same units and form as Pressure Normalized Rate.

Alternatively, PI is the production flow rate (q) over the drawdown pressure (Δp), which can be expressed below:

for oil

for gas

Where:

q_o = oil rate

P_R = Reservoir Pressure

P_wf = Sandface Flowing Pressure

q_g = gas rate

Psi_R = Reservoir Pseudo-Pressure

Psi_wf= Sandface Flowing Pseudo-Pressure