Petroleum Goodies: Modified Hyperbolic Decline Curve

Posted: 02 Sep 2012 04:10 AM PDT

Modified Hyperbolic Decline Curve Formula

Extrapolation of hyperbolic declines over long periods of time frequently results in unrealistically high reserves. To avoid this problem, it has been suggested (Robertson) that at some point in time, the hyperbolic decline be converted into an exponential decline.⁽¹⁾

This Excel tool is useful to forecast a gas well from historical production. Historical productions are used to history match to get decline parameters such as initial rate (qi), decline rate (D) and b value. A value of b = 0 corresponds to exponential decline. A value of b = 1 is called harmonic decline. Sometimes, values of b > 1 are observed. This forecasting tool is built using two decline schedules, the first schedule used hyperbolic decline (b > 1) and the second part utilized exponential decline (b = 0). The change in decline type is indicated by switch rate. Decline conversion from effective to nominal (vice versa) has been calculated in this tool.⁽²⁾

Feel free to use this tool and don’t forget to Like it and share it with your friends.

Using VBA macro? No

References:

Fekete Decline Curve Analysis
Schlumberger Oil Field Manager (OFM)

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Sunday, September 2, 2012