Page 362 - Petrophysics 2E

330 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

OF
CENTRIFUGE MEASUREMENT CAPILLARY PRESSURE

LABORATORY PROCEDURE

The centrifuge procedure that is in general use now was introduced
by Slobod et al. in 1951 [15]. The core is placed in a cup containing
an extended calibrated small-diameter tube where fluids displaced from
the core by centrifugal force are collected (Figures 5.14 and 5.15). A
step-by-step procedure was presented by Donaldson et al. [ 161.

1. A weighed and measured core is saturated with brine under vacuum
and then re-weighed to determine the weight of brine saturating
the core (wb). The volume of brine in the saturated core (Vw) is
then determined by dividing the weight of the brine by its density,
and the porosity is determined by dividing the volume of water in
the saturated core by the bulk volume of the core (vb): Vw = Wb/&
$ = vw/vb.
2. The core is placed in the core holder, which is then filled with oil to
cover the core. The core holder is placed in the centrifuge shield and
then attached to the centrifuge arm.

Figure 5.14. Positlorn of core and core bolder in a centrifige for measurement of
oikiisplaeingwater capiUaty pressure curves f 1 GI.