$\begin{array}{l}\displaystyle p = \frac{1}{N_\alpha} \sum_\alpha p_\alpha\end{array}$

where

$\begin{array}{l}p_\alpha\end{array}$	formation pressure of $\begin{array}{l}\alpha\end{array}$ -phase
$\begin{array}{l}N_\alpha\end{array}$	number of fluid phases

3-phase pressure

In case of the most popular 3-phase Oil + Gas + Water fluid model:

$\begin{array}{l}\displaystyle p = \frac{1}{3} \left( p_o + p_g + p_w \right)\end{array}$

where

$\begin{array}{l}p_o\end{array}$	formation pressure of oil phase
$\begin{array}{l}p_g\end{array}$	formation pressure of gas phase
$\begin{array}{l}p_w\end{array}$	formation pressure of water phase

All three pressures are connected via Capillary pressures $\begin{array}{l}p_{cow} = p_o - p_w\end{array}$ and $\begin{array}{l}p_{cog} = p_o - p_g\end{array}$ as following:

$\begin{array}{l}\displaystyle p_o = p + p_{co}\end{array}$

$\begin{array}{l}\displaystyle p_{co} = \frac{1}{3} \cdot (p_{cow} + p_{cog)\end{array}$

$\begin{array}{l}\displaystyle p_g = p + p_{cg}\end{array}$

$\begin{array}{l}\displaystyle p_{cg} = \frac{1}{3} \cdot (p_{cow} - 2 \cdot p_{cog} )\end{array}$

$\begin{array}{l}\displaystyle p_w = p + p_{cw}\end{array}$

$\begin{array}{l}\displaystyle p_{cw} = \frac{1}{3} \cdot ( -2 \cdot p_{cow} + p_{cog} )\end{array}$

Page tree

See Also

Page tree

Multiphase formation pressure

See Also