Fetkovich (1968) improved on earlier work by Arps in predicting the declining production rate of oil and gas wells. He suggested that experimental production rate data could be overlaid on a graph and matched to a series of type curves. The production rate is then extrapolated into the future with the assistance of the curves.

The Excel spreadsheet reproduces the plot given in Figure 8 of the following reference.

Fetkovich, M.J., "Decline Curve Analysis Using Type Curves", Journal of Petroleum Technology (June 1980) 1065-77.

The decline curve rate-time equations are given below.

where

- n is a factor that governs the shape of the back pressure curve
- q
_{Dd}is the decline curve dimensionless production rate - t
_{Dd}is the decline curve dimensionless time