Experiments on the Capillary Properties of Porous Solids

Abstract

Abstract A report is made of experimental work performed on the capillary retentionof water within porous solid systems, the displacement being accomplished withair and various organic liquids. A portion of the experiments were designed tomeasure the lowering of vapor pressure of water within a porous solid withsubsequent conversion of such vapor pressure data to capillary pressure values.The form of the capillary pressure curve at high capillary pressures has beenelucidated from this data. Certain theoretical approaches are presented toindicate the correlation between work done by previous investigators. Thepresent work is correlated also with theory. Surface area values are calculatedfor the various core systems studied. Introduction Leverettt in 1941 presented a paper which gave the essential concepts ofcapillary behavior in porous solids. His presentation included both theoreticaland experimental aspects of the problem. He defined the term "capillarypressure" and applied it to an ideal porous system. His work included thedefinition of a dimensionless quantity which was a function of fluid saturationand which could be correlated with porosity and permeability for clean, unconsolidated sands. His experimental work was performed by the drainage ofwater from packed columns of unconsolidated sands. Subsequently, other authorshave presented experimental techniques which permit the determination ofcapillary pressure data on small core samples. Data have been presented onporous systems other than unconsolidated sand and with the use of liquids otherthan water. Notable among these are the works of Hassler, Brunner and Deahl, Bruce and Welge, Amyx and Yuster, and Purcell. Others have indicated theapplicability of such data to field problems without regard to the theoreticalaspects of the capillary pressure saturation function. Within the recentpublished literature there have also been reported studies of the correlations between capillary pressure data and otherfundamental properties of porous solids. It was the intent of the presentreported work to investigate the behavior noted by water and various otherliquids within porous systems in an attempt to amplify existing correlationsbetween capillary properties, surface properties, and other fundamentalcharacteristics of porous systems. The experimental work described here wasperformed as two different investigations but due to its nature it is reportedas separate phases of the same general topic. T.P. 2640