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Unconstrained
Unconstrained
Unconstrained matching

All three model parameters 

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body--uriencoded--\%7B q%5e*_0, \, D_0, \, b \%7D
 are being varied to achieve the best fit to the training dataset.

Exponential Production DeclineHyperbolic Production DeclineHarmonic Production Decline

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bodyb=0

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body0<b<1

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bodyb=1

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q(t)=qq^*_0 \exp \left( -D_0 \, t \right)
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q(t) = \frac{qq^*_0}{ \left( 1+b \cdot D_0 \cdot t \right)^{1/b} }
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q(t)=\frac{qq^*_0}{1+D_0 \, t} 
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Q(t)=\frac{qq^*_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{qq^*_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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Initial
Initial
Match the value of the initial rate 
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body--uriencoded--q%5e*(t=0) = q_0

The value of the model rate at the initial time moment is set to training dataset: 

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body--uriencoded--q%5e*(t=0) = q_0
 and the two other model properties
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body--uriencoded--\%7B D_0, \, b \%7D
 are being varied to achieve the best fit to the training dataset.

Exponential Production DeclineHyperbolic Production DeclineHarmonic Production Decline

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bodyb=0

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body0<b<1

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bodyb=1

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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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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:

Exponential Production DeclineHyperbolic Production DeclineHarmonic Production Decline

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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)}





See Also

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Petroleum Industry / Upstream /  Production / Subsurface Production / Field Study & Modelling / Production Analysis / Decline Curve Analysis / DCA Arps @model

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