Page tree

Versions Compared

Key

  • This line was added.
  • This line was removed.
  • Formatting was changed.


In case the phases have the same pressure the compressibility of multi-phase fluid can be expressed via compressibilities of single-phase fluids as: Compressibility of multiphase fluid in thermodynamic equilibrium at a given pressure 

LaTeX Math Inline
bodyp
 and temperature 
LaTeX Math Inline
bodyT
  is a linear sum of its single-phase components:

LaTeX Math Block
anchorcf1
alignmentleft
c_f(p, T) = c\sum_w {\,alpha} s_w\alpha +\cdot c_o \, s_o + c_g \, s_g_\alpha(p,T)

where

LaTeX Math Inline
bodys_\alpha

LaTeX Math Inline
body\alpha
-phase volume share, subjected to
LaTeX Math Inline
body\sum_{\alpha} s_\alpha = 1

LaTeX Math Inline
bodyc_\alpha(p, T)

LaTeX Math Inline
body\alpha
-phase compressibility as function of pressure 
LaTeX Math Inline
bodyp
 and temperature 
LaTeX Math Inline
bodyT
 



Expand
titleDerivation


Panel
borderColorwheat
borderWidth10

The total multiphase volume:

LaTeX Math Block
anchor1
alignmentleft
V
_f
 = 
V_w \, s_w +
\sum V_
o \, s_o + V_g \, s_g
where
\alpha


where

LaTeX Math Inline
bodyV_\alpha
are volumes, occupied by individual phases.


The volume fraction of individual phase is defined as:

LaTeX Math Block
anchor1
alignmentleft
s_
w = \frac{V_w}{V_f}, \ s_o
\alpha = \frac{V
_o}{V_f}, \ s
_
g = \frac{V_g
\alpha}{V
_f
}


This leads to:

LaTeX Math Block
anchor1
alignmentleft
c_f = \frac{1}{V
_f
} \, \frac{\partial V
_f
}{\partial p} = 
\frac{1}{V
_f
} \sum_\
,
alpha \frac{\partial V_
w
\alpha}{\partial p} 
+
= 
 \
frac{1}{V_f}\,
sum_\alpha \frac{
\partial
V_
o
\alpha}{
\partial p
V} 
+
\, \frac{1}{V_
f
\alpha}
\,
 \frac{\partial V_
g
\alpha}{\partial p} =
 \sum_\alpha s_\alpha \, c_\alpha




In most popular practical case of a 3-phase fluid model this will be: 

1cf
c_w + s_o \, c_o + s_g \, c_g
LaTeX Math Block
anchor
cf
alignmentleft
c_f = 
\frac{V
s_w
}{V_f}
 \, 
\left( \frac{1}{V_w} \, \frac{\partial V_w}{\partial p} \right) + \frac{V_o}{V_f} \, \left( \frac{1}{V_o} \, \frac{\partial V_o}{\partial p} \right) + \frac{V_g}{V_f} \, \left( \frac{1}{V_g} \, \frac{\partial V_g}{\partial p} \right)which leads to
LaTeX Math Block Reference
anchor

where 

LaTeX Math Inline
body\{ w, \, o, \, g \}
 mean water phase, oil phase and gas phase.


See also

...

Physics / Mechanics / Continuum mechanics / Fluid Mechanics / Fluid Statics / Fluid Compressibility / Fluid Compressibility @model