Apparatus and method for measuring the capillary pressure distribution

Abstract

A capillary pressure measuring device comprises a highly regulated low pressure control system with a vacuum producing subsystem, a sample holder, a vertical positioning mechanism and a weighing device used for measuring the advancing and receding capillary pressure distributions of porous materials using a wetting fluid. Advancing capillary pressure distribution of the porous materials are measured by the steps of applying a highly controlled pressure to a test sample which is in contact with the wetting fluid, so as to allow no or only limited absorption of the fluid in the sample; incrementally reducing the applied pressure and recording the stable or equilibrium fluid weight adsorbed at each increment of the reduced pressure; and calculating the advancing average sample cross section area based capillary pressure distribution and the pore size distribution using the weight absorbed versus applied pressure data. Receding capillary pressure distribution of the porous materials are measured by the steps of saturating the test sample with the wetting fluid; incrementally increasing the applied pressure and recording the release of the absorbed fluid from the test sample; and calculating the receding capillary pressure distribution and the receding average sample cross section area based pore size distribution based on the similar weight versus applied pressure data.