Capillary pressure scanning curves by the micropore membrane technique

Experimental procedures have been developed for capillary pressure hysteresis measurements. Capillary drainage and imbibition bounding curves (complete bounding cycle) and a number of scanning curves have been measured for a water-wet Berea core and an oil-wet reservoir core by the micropore membrane technique. The curves are measured both with stepwise and continuous change of the differential pressure. A continuous and slow change of capillary pressure gives considerable savings in experimental time. Reversibility of scanning curves is observed for the Berea core when the range of saturation reversal is less than 5% and may be explained by a pinning effect. The oil-wet reservoir core, however, exhibits a hysteresis loop even for this small saturation range. For saturation reversals in excess of 5%, the scanning curves for both samples form closed loops that are similar in shape to the bounding loop, i.e., for each sample, all hysteresis loops have the same shape but different sizes. This fact may be used to improve the algorithm for hysteresis modelling.