The quantitative measure of volatile oil in gas phase.
where
V_{Gg}^{\LARGE \circ}= \frac{m_{Gg}}{\rho_G^{\LARGE \circ}} – STP volume of natural gas component of mass
m_{Gg} and STP density
\rho_G^{\LARGE \circ}
R_v(p, T) is a function of pressure and temperature due to oil-gas exchange
R_v = \frac{V_{Og}^{\LARGE \circ}}{V_{Gg}^{\LARGE \circ}} =
\frac{m_{Og}}{ m_{Gg}} \cdot \frac{\rho_G^{\LARGE \circ}}{\rho_O^{\LARGE \circ}}
V_{Og}^{\LARGE \circ}= \frac{m_{Og}}{\rho_O^{\LARGE \circ}} – STP volume of dead oil component of mass
m_{Og} and STP density
\rho_O^{\LARGE \circ}