SHF capillary pressure model
Physical method based on the following formula:
based on implicit solution of the constant pressure gradient equation: where
\rho_o=\rho_o(T_i, \, p_i) и
\rho_w=\rho_w(T_i, \, p_i) – oil and water densities at initial formation temperature
T_i and pressure
p_i. This model requires reliable and representative data bank on capillary pressure at sandface conditions.
(1)
s_{wi}(h)=P_{cow}^{-1}[(\rho_w -\rho_o) g (h-h_{FWL})]
(2)
(\rho_w -\rho_o) \cdot g \cdot (h-h_{FWL}) = P_{cow}(s_{wi})
SHF Skelt-Harrison model
Empirical method based on the following formula:
where model parameters
\{ a, \ b, \ c, \ d \} are calibrated on water saturation from OH logs for each lithofacies or petrotype individually. The coefficient
c is related to FWL correction but usually set the same for all lithofacies / petrotypes of a given reservoir unit. If core data is abundant then one can build a reasonable correlation of model parameters on porosity
\phi and/or permeability
k_a:
(3)
s_{wi}(h) = 1 - a \exp \left( -\left(\frac{b}{h-h_{FWL}+d}\right)^c \right)
(4)
a = a(\phi, k_a), \; b = b(\phi, k_a), \; c = c(\phi, k_a)
SHF Cuddy model
Empirical method based on the following formula:
where model parameters
\{ a, \ b, \ c \} are calibrated on water saturation from OH logs for each lithofacies or petrotype individually. The coefficient
c is related to FWL correction but usually set the same for all lithofacies / petrotypes of a given reservoir unit. If core data is abundant then one can build a reasonable correlation of model parameters on porosity
\phi and/or permeability
k_a:
(5)
s_{wi}(h) = \frac{b}{\phi} \; (h-h_{FWL}-c)^{\ a}
(6)
a = a(\phi, k_a), \; b = b(\phi, k_a), \; c = c(\phi, k_a)
See also
Physics / Fluid Dynamics / Percolation
Petroleum Industry / Upstream / Subsurface E&P Disciplines / Field Study & Modelling / Petrophysics / Saturation Height Function (SHF)
[ Basic reservoir properties ]
References
| 1 | SPE 71326, B. Harrison (Enterprise Oil), X.D. Jing (Imperial College, London), Saturation Height Methods and Their Impact on Volumetric Hydrocarbon in Place Estimates, 2001 |