(1)	$\begin{array}{l}\displaystyle \Delta Q_N = \frac{\Delta Q}{V_e}\end{array}$

(2)

$\begin{array}{l}\displaystyle \Delta Q = - \frac{B_o - R_s \, B_g}{1- R_s \, R_v} \cdot \, Q^{\uparrow}_O + \frac{ B_g - R_v \, B_o}{1- R_s \, R_v} \cdot \, \left( Q^{\downarrow}_G - Q^{\uparrow}_G + Q^{\downarrow}_{GCAP} \right) + B_w \, \left( Q^{\downarrow}_W - Q^{\uparrow}_W + Q^{\downarrow}_{WAQ} \right)\end{array}$

where

$\begin{array}{l}\Delta Q(t)\end{array}$	Cumulative Voidage Replacement Balance (CVRB) over time $\begin{array}{l}t\end{array}$
$\begin{array}{l}V_e = V \cdot \phi_i\end{array}$	initial drainage volume of the main pay (excluding the aquifer and gas cap)
$\begin{array}{l}\phi_i = \phi(p_i)\end{array}$	initial porosity

If Aquifer Expansion and/or Gas Cap expansion are unknown they are simply ignored for the first pressure modelling run: $\begin{array}{l}Q^{\downarrow}_{GCAP} = 0, \ Q^{\downarrow}_{WAQ} = 0\end{array}$ .

They can be adjusted at the next model runs by fitting formation pressure response (see Material Balance Pressure @model).

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See Also

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Normalized Cumulative Voidage Replacement Balance = NVRB

See Also