Spontaneous imbibition characteristics of diatomite

A systematic investigation of fluid flow characteristics within diatomite ( a high porosity, low permeability, siliceous rock) is reported. Using an X- ray computerized tomography (CT) scanner, and a novel, CT-compatible imbibi tion cell, we study spontaneous cocurrent water imbibition into diatomite s amples. Air-water and oil-water systems are used and the initial water satu ration is variable. Mercury porosimetry and a scanning electron microscope (SEM) are employed to describe diatomite pore structure and the rock framew ork. Diatomite exhibits a fine pore structure and significant pore-level ro ughness relative to sandstone thereby aiding the flow of imbibing water. De spite a marked difference in permeability and porosity as compared to sands tone, we find similar trends in saturation profiles and dimensionless weigh t gain vs. time functions. Although diatomite is roughly 100 times less per meable than sandstone, capillary forces result in a strong imbibition poten tial for water such that imbibition rates rival and surpass those for sands tone (C) 2000 Elsevier Science B.V. All rights reserved.