Bubblepoint pressure

Bubblepoint pressure is the pressure at which the first bubble of gas evolves as the pressure decreases. Three methods for estimating bubblepoint pressure of the oil at reservoir conditions are presented.

1. Standing (1947)
$$P_b=a_1{(R_s/{\gamma }_g)}^{a_2}{{}_e}^{a_{3}T+a_4{\gamma }_{API}}$$ $$\overline{)\begin{array}{}\text{Coefficient}\text{Original}\\ a_1& 18\\ a_2& 0.83\\ a_3& 2.09535x{10}^{-3}\\ a_4& -28.78231x{10}^{-3}\end{array}}$$




2. Vasquez & Beggs (1980)
$$P_b=a_1{(R_s/{\gamma }_g)}^{a_2}{{}_e}^{a_3{\gamma }_{API}/(T+460)}$$ $$\overline{)\begin{array}{}\text{Coefficient}\text{Original}\\ \text{For}{\gamma }_{\text{API}}\le \mathrm{30\; :}\\ a_1& 20.7880\\ a_2& 0.9143\\ a_3& -23.5202\\ \text{For}{\gamma }_{\text{API}}>\mathrm{30\; :}\\ a_1& 29.7818\\ a_2& 0.8425\\ a_3& -20.1609\end{array}}$$




3. Al-Marhoun (1988)
$$P_b=a_1{R}_s{}^{a_2}{\gamma }_g{}^{a_3}{\gamma }_o{}^{a_4}{(T+460)}^{a_5}$$ $$\overline{)\begin{array}{}\text{Coefficient}\text{Original}\\ a_1& 5.38088x{10}^{-3}\\ a_2& 0.715082\\ a_3& -1.87784\\ a_4& 3.14370\\ a_5& 1.32657\end{array}}$$