Pore size distribution is one of the most important reservoir rock properties. The purpose of this report is to calculate and evaluate pore size distribution from capillary pressure curves using the centrifuge method.
The core samples used in this experimental work were Berea Sandstone, Abu-Dhabi Dolomite and Japanese Sandstone. Reservoir rocks were frozen using liquid nitrogen and small core plugs were cut and recovered from them.
Capillary pressure of small core plugs was measured using the centrifuge method. Pore size distribution was calculated and evaluated from their capillaly pressure curves.
After analyzing the graphical representation of these data, the following points are reached:
(1) In Berea Sandstone, the slopes of capillary pressure curves were very steep and most of pore radii distributed 4-5μm.
(2) In Abu-Dhabi Dolomite, the slopes of capillary pressure curves were relatively steep and pore radii distributed narrowly.
In addition, irreducible water saturations were low. This is due to the nonwetting characteristic of Dolomite with respect to water.
(3) In Japanese Sandstone, the slopes of capillary pressure curves were relatively gentle and pore radii distributed widely.
In addition, irreducible water saturations were high. This is due to the wetting characteristic of Sandstone with respect to water.
The centrifuge method for the determination of capillary pressure and pore size distribution is proved to be very effective. This is mainly due to the repeatability in conducting capillary pressure experiments and the number of cores that can be tested at the same time using this method.
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