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Exponential Production DeclineHyperbolic Production DeclineHarmonic Production Decline

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q(t)=q_0 \exp \left( -D_0 \, t \right)
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q(t) = \frac{q_0}{ \left( 1+b \cdot D_0 \cdot t \right)^{1/b} }
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q(t)=\frac{q_0}{1+D_0 \, t} 
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Q(t)=\frac{q_0-q(t)}{D_0}
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Q(t)=\frac{q_0}{D_0 \, (1-b)} \, \left[ 1- \left( \frac{q(t)}{q_0} \right)^{1-b}  \right]
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Q(t)=\frac{q_0}{D_0} \, \ln \left[ \frac{q_0}{q(t)} \right] =  \frac{q_0}{D_0} \ln q_0 + \frac{q_0}{D_0}  \cdot \ln q(t)
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Q_{\rm max}=\frac{q_0}{D_0}
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Q_{\rm max}=\frac{q_0}{D_0 \cdot (1-b)}
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Q_{\rm max}=\infty
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D(t) = D_0 = \rm const
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D(t) =\frac{D_0}{1+ b \cdot D_0 \cdot t}
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D(t) = \frac{D_0}{1+ D_0 \cdot t}
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anchortau_exp
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\tau(t) = \tau_0 = \rm const
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\tau(t) = \tau_0 + b \cdot t
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\tau(t) = \tau_0 + t
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\mathrm{RPR}(t) = \tau(t) = \tau_0 = \rm const
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\mathrm{RPR}(t) = \tau_0 \, \left[ 
1 + \frac{b }{(1-b)} \cdot \frac{q_0}{q(t)}
\right]


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\mathrm{RPR}(t) = \infty

To ensure the smooth transition from historical data

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body[(t_1,q_1)... (t_N, q_N)]
 to the production forecasts in future time moments
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body--uriencoded--[(t_%7BN+1%7D,q_%7BN+1%7D), ...]
one may wish to constrain the model by firm matching the production at the last historical moment
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body(t_N, q_N)
 which leads to the following form of Arp's model:

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q(t)=q_N \cdot \exp \big[ -D_0 \cdot (t-t_N) \big]

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q(t) = q_N \cdot \left[ \frac{1+b \cdot D_0 \cdot t_N }
{ 1+b \cdot D_0 \cdot t  } \right]^{1/b}

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q(t) =  q_N \cdot  \left[ \frac{1+D_0 \cdot t_N }
{ 1+ D_0 \cdot t  } \right]

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Q(t) - Q_N = [ q_N - q(t)] \, \tau_0

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Q(t) - Q_N = \frac{q_N^b \, (\tau_0 + b \, t_N)}{1-b} \left[ q_N^{1-b} - q^{1-b}(t) \right]

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Q(t) - Q_N = q_N \, (\tau_0 + t_N) \cdot \ln \frac{q_N}{q(t)}


The Exponential and Hyperbolic decline are applicable for Boundary Dominated Flow with finite reserves

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body--uriencoded--Q_%7B\rm max%7D \leq \infty
 while Harmonic decline is associated with production from the reservoir with infinite reserves
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body--uriencoded--Q_%7B\rm max%7D = \infty
.

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