J.J. Arps, American geologist who first formalized in mathematical terms the rate at which oil production from a single well declines over time (1945). He demonstrated that oil well production follows a predictable pattern, modeled by a decline curve. The decline curve pattern goes as follows: production will increase for a short period, then production will reach a peak followed by a long and slow decline. The shape of this decline curve, how high the production peaks are, and the length of the decline are all driven by reservoir conditions. Production decline was considered to be proportional to pressure decline through assumptions of constant wellbore pressure and constant productivity index. Exponential, hyperbolic, and harmonic decline curves are possible, depending on the specifics of individual oil wells. In various forms, the decline curve is still widely used today to forecast future production.

Source

• Cleveland, Cutler (Lead Author); Tom Lawrence (Topic Editor). 2008. "Arps, J.J.." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth June 15, 2006; Last revised April 14, 2008; Retrieved June 30, 2009]. <http://www.eoearth.org/article/Arps,_J.J.>