where
\sigma_{ow}
\sigma_{og}
\theta_{ow}
\theta_{og}
k
\phi
J_{cog}(s_g) The functions
J_{cow}(s_w) and
J_{cog}(s_g) are called Leverett J-functions. They are individual to every certain rock type, just like relative permeability curves. There are many correlations for Leverett J-functions and the most popular is Brooks-Corey correlation: where
s_{wn} = \frac {s_w - s_{wс}}{1-s_{wс}} – normalised water saturation,
s_{wс} – critical water saturation,
a, \lambda – model parameters which are set for laboratory data on capillary pressure and/or on resistivity water saturation during SHF. Model parameter
\lambda is related to the the size of the pore size distribution. The most popular value is 2 but it can vary to smaller or higher values.
Physical correlation for capillary pressure on reservoir saturation:
(1)
P_{cow} (s_w) = \frac{ (\sigma \cos \theta) _{ow} } { \sqrt \frac{k}{\phi}} \; J_{cow}(s_w)
(2)
P_{cog} (s_g) = \frac{ (\sigma \cos \theta)_{og} } { \sqrt \frac{k}{\phi}} \; J_{cog}(s_g)
oil-water surface tension oil-gas surface tension oil-gas contact angle oil-gas contact angle absolute permeability to air porosity some function of water saturation some function of gas saturation
(3)
J_{cow}(s_w) = a \ ( s_{wn} )^{-1 / \lambda}
See also
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Petrophysics / Capillary pressure / Capillary pressure @model