Abstract
Gas flow through porous media in the slip flow regime is of great significance for the exploitation of undergroundnatural gas and oil. The gas slip effect in porous media plays a very important role in different engineeringfields, because gas slippage is involved in the determination of gas apparent permeability. In thisstudy, the gas slip effect was investigated in model microporous materials: composite silica aerogels. We measuredgas and water permeability in sets of nano composite silica aerogels, fractal materials with a high porevolume and tortuosity, and low permeability. The observed difference in gas and water permeability was analyzedfrom the point of view of the slip regime (Klinkenberg correction), b) and transition regime (Knudsencorrection). The effect of structural parameters of porous media (pore volume, tortuosity, fractal features) on theKlinkenberg and Knudsen corrections are discussed and the different models proposed in the literature aretested. Experimental results showed that: (1) gas permeability is almost two orders of magnitude greater thanwater permeability, (2) Klinkenberg and Knudsen corrections increase with decreasing permeability, (3) theKnudsen corrections calculated from the literature models were almost one order of magnitude lower thanexperimental data, (4) we also tested the Klinkenberg approach for tortuous and fractal porous media, the fractalmodel with second-order slip improved the accuracy of the prediction and agree with the experimental results.