New Experimental Approach for Measuring Drainage and Spontaneous Imbibition Capillary Pressure

This research presents a visualizing method to estimate capillary pressure relationship from centrifuge experiments using spinning disk geometry. The visualizing method consists of continuously recording the local saturation variation by using a video camera while centrifuging at any given time. The experimental procedure consists of recording sample images and fluid production at any given time and then determines local saturation by a simple correlation between production and gray level. Thus, a modified core holder was designed to adopt the new approach. The core holder must be transparent for visual interpretation of the experiments and strong to account for the high pressure during experiments. The traditional geometry for the centrifuge method is well-established in the industry. However, the benefits of using the spinning disk approach consist of validity of zero capillary pressure at the outlet face, ability of measuring local saturation at any given time, possibility of estimating drainage and spontaneous imbibition capillary pressure, and consideration of radial effect. Results of 24 rock samples show a good agreement between the capillary pressure relationships obtained from the new approach and those obtained from the porous-plate method. Relative errors of the capillary pressure were less than 5% for most samples. Furthermore, the entry pressures and irreducible wetting phase saturations obtained by this approach were agreed with the porous plate method.