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q(t)=q_0 \exp \left( -D_0 \, t \right)



LaTeX Math Block
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Q(t)=\frac{q_0-q(t)}{D_0}



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Q_{\rm max}=\frac{q_0}{D_0}



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D(t)=D_0 = \rm const


where

LaTeX Math Inline
bodyq_0 = q(t=0)

Initial production rate of a well (or groups of wells)

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bodyD

model parameter

_0 > 0

initial Production decline rate which in this specific case

coincides with a constant Production decline rate

stays consant: 

LaTeX Math Inline
bodyD(t) = D_0 = \rm const

LaTeX Math Inline
body--uriencoded--\displaystyle Q(t)=\int_0%5et q(t) \, dt

cumulative production by the time moment 

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bodyt

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body--uriencoded--Q_%7B\rm max%7D =\int_0%5e%7B\infty%7D q(t) \, dt

Estimated Ultimate Recovery (EUR)

LaTeX Math Inline
body--uriencoded--\displaystyle D(t) = - \frac%7Bdq%7D%7BdQ%7D

Production decline rate


It can be applied to any fluid production: 
water, oil or gas. 

Exponential Production Decline has a physical meaning of producing from a the finite-volume reservoir with finite reserves 

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body--uriencoded--Q_%7B\rm max%7D
under Pseudo Steady State (PSS) conditions, resulting in constant Production decline rate 
LaTeX Math Inline
bodyD(t) = D_0 = \rm const
.


A typical example of various fitting efforts of Exponential Production Decline are brought on Fig. 1 – Fig. 3 with exponential fitting being a clear winner.

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Fig. 1. Exponential best fit to Exponential Production DeclineFig. 2. Hyperbolic best fit to Exponential Production DeclineFig. 3. Harmonic best fit to Exponential Production Decline


See Also

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Petroleum Industry / Upstream /  Production / Subsurface Production / Field Study & Modelling / Production Analysis / Decline Curve Analysis

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