Page 279 - Standard Handbook Petroleum Natural Gas Engineering VOLUME2

Decline-Curve Analysis 447

Table 5-33
Classification of Production Decline Curves
1. Constant II. Hyperbolic 111. Harmonic
Decline type percentage decllne decllne decllne
Basic Decline is constant Decline is proportional Decline is propor-
characteristic n=O to a fractional power tional to a production
(n) of the production rate
rate n=l
Oencl
Rate-time q = q,e-"
relationship

From Reference 255.
a = decline as a fraction of production rate qi = an initial production rate
t = time n = exponent
ai = initial decline q = production rate at time t
N, = cumulative oil production et time t h = lln

and the flow rate at time, t, is:

9 qi + ?JpPan(l - d) (5-188)
Hyperbolic Decline

As shown in Table 5-33, the timerate relationship for the hyperbolic decline is:

(5-189)

If h is substituted for l/n, the time-rate relationship is:

9i
9=
(I+?] (5-190)

where h is the hyperbolic decline constant.