For volatile oil fluid model the gas surface flowrate $\begin{array}{l}q_G\end{array}$ is related to gas sandface flowrate $\begin{array}{l}q_g\end{array}$ and oil sandface flowrate $\begin{array}{l}q_o\end{array}$ as (see derivation):

(1)	$\begin{array}{l}\displaystyle q_G =(1-R_v \, R_s)^{-1} \left( \frac{q_g}{B_g} +\frac{R_s \, q_o}{B_o} \right)\end{array}$

where

$\begin{array}{l}B_o, B_g\end{array}$	oil formation volume factor between separator and sandface pressure/temperature conditions
$\begin{array}{l}R_s\end{array}$	Solution GOR at sandface pressure/temperature conditions

It relates to Liquid production rate at surface as:

(2)	$\begin{array}{l}\displaystyle q_G = GOR \cdot (1-Y_w) \, q_L\end{array}$

It simplifies for the Black Oil model to:

(3)	$\begin{array}{l}\displaystyle q_G = \frac{q_g}{B_g}\end{array}$

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