Synonym: Modified Black Oil fluid @model = MBO fluid @model = Volatile Oil fluid @model

Specific case of a 3-phase fluid model based on three pseudo-components :

	water pseudo-component, which may include minerals (assuming formation water and injection water composition is the same)
	dead oil pseudo-component
	dry gas pseudo-component

existing in three possible phases :

	water phase, consisting of Water component only
	oil phase, consisting of dead Oil pseudo-component and dissolved dry Gas pseudo-component t (called Solution Gas)
	gas phase, consisting of dry Gas pseudo-component and vaporized dead Oil pseudo-component (called volatile oil)

The volumetric phase-balance equations is:

s_w + s_o + s_g =1

where

	share of total fluid volume occupied by water phase
	share of total fluid volume occupied by oil phase
	share of total fluid volume occupied by gas phase

The accountable cross-phase exchanges are illustrated in the table below:


✔
	✔	✔
	✔	✔

Modified Black Oil fluid @model is widely used to model Volatile Oil Reservoir and Pipe Flow Simulations.

The relations between in-situ (at given temperature and pressure) and STP masses, volumes, densities and compressibilities are given by the following equations (see Derivation):

V_O = \frac{V_o}{B_o} + R_v \,\frac{V_g}{B_g}

V_G = \frac{V_g}{B_g} + R_s \, \frac{V_o}{B_o}

V_W =  \frac{q_w}{B_w}

V_L =  V_O + V_W

V_o = \frac{B_o \cdot (V_O - R_v \, V_G)}{1- R_v \, R_s}

V_g = \frac{B_g \cdot (V_G - R_s \, V_O)}{1- R_v \, R_s}

V_w = B_w \cdot V_W

V_t = V_o + V_g + V_w

In-situ oil-cut:

s_o = V_o/V_t

In-situ gas-cut:

s_g = V_g/V_t

In-situ water-cut:

s_w = V_w/V_t

s_o+s_g+s_w = 1

Surface oil mass rate:

m_O = \rho_O V_O

Surface gas mass rate:

 m_G = \rho_G V_G

Surface gas mass rate:

m_W = \rho_W V_W

Surface total fluid mass rate:

m = m_O + m_G + m_W

In-situ oil mass:

m_o = (\rho_O + \rho_G \cdot R_s) \cdot \frac{V_o}{B_o}

In-situ gas mass:

m_g = (\rho_G + \rho_O \cdot R_v) \cdot \frac{V_g}{B_g}

In-situ water mass:

m_w = \rho_W \cdot V_w/B_w

In-situ total fluid mass:

m = m_o + m_g + m_w

In-situ oil density:

\rho_o = \frac{\rho_O + \rho_G \cdot R_s}{B_o}

In-situ gas density:

\rho_g = \frac{\rho_G + \rho_O \cdot R_v}{B_g}

In-situ water density:

\rho_w = \frac{\rho_W}{B_w}

In-situ Total fluid density:

\rho_t = m/V_t = s_o \, \rho_o + s_g \, \rho_g + s_w \, \rho_w

In-situ total fluid compressibility:

c = \rho_t^{-1} \cdot ( s_o \, \rho_o \, c_o + s_g \, \rho_g \, c_g + s_w \, \rho_w \, c_w )

where are Dynamic fluid properties.

See Also