ABSTRACT
A commercially available centrifuge was modified to measure drainage capillary pressures of various core samples at temperatures up to 400°F. The modifications provided good control over the following core parameters that needed to be accurately measured: maximum capillary pressure, average wetting phase saturation, and temperature. Measurements were made on twelve core samples of various lithologies, with 5% sodium chloride brine as the wetting phase fluid and either nitrogen or McKittrick crude oil as the non-wetting phase fluid, in the following increasing temperature sequence: 105°F, 200°F, 300°F, and 400°F. The lithologies investigated were as follows: clean sandstones, shaly sandstones, and limestone.
The results of this study showed that for the McKittrick crude oil-brine system, the irreducible brine saturation increased with increase in temperature for all lithologies confirming the results of previous investigators. However, for the nitrogen-brine system, irreducible brine saturation was found to decrease with increase in temperature for all lithologies.
The interplay of the effects of capillary and viscous forces as temperature increases is given as a possible explanation for the observed phenomena. Also the implications of these results as applied to formation evaluation and reservoir engineering are discussed.