Page 382 - Petrophysics 2E

350 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

where:

(1) subscript i indicates the individual cores tested, and
(2) subscript j indicates values of J and Pc with respect to the specific
core and data point (Swij).

After the J-versus-S, data have all been assembled, the single (average)
curve may be obtained using the hyperbolic function:

(5.65)

The geometric average of the permeability and the arithmetic average
of the porosity are used in Equation 5.65. Using these data and the average
J-curve, the single correlated capillary pressure curve may be obtained
from Equation 5.64 and used to determine the reservoir saturation profile
as discussed.

EXAMPLE

The core data in Table 5.3 were obtained for four cores extracted
from the same formation. Calculate the vertical saturation profile and
determine the Iocations (heights above the free water level) of the
oil-water contact, So, and Si,. The interfacial tension is 25 N x 10-3/m,
the density difference between the brine and oil is 0.80 g/cm3, the
residual oil saturation is 30%, and Si, occurs at S, = 0.20.

SOLUTION

The average permeability is:

1
logE = x [log (0.60) + log (0.095) + log (0.132) + log (0.155)]

k = 0.104 D

The average porosity is:

4 - - x L0.18 + 0.20 + 0.21 + 0.231
1
-4

Q = 0.21