Decline-curve Analysis

Abstract

Two types of decline curves are considered and their applications arediscussed. The first is the well-known semilogarithmic decline curve having therate of production plotted on the logarithmic scale and the time on thehorizontal scale. The other curve is the percentage of oil in the fluid versuscumulative production, and it is plotted on Cartesian coordinate paper. Thesecurves are illustrated by carefully and adequately labeled graphs. Whereconditions permit application of both types of curves for rationallydetermining the reserves of a well, both should be applied and the mostconservative reserve should be chosen. Formulas are given for determining theeconomic limits. The semilogarithmic decline curve is treated first.