Publication Details

Category Text Publication
Reference Category Journals
DOI 10.1002/2013WR014657
Title (Primary) Quantification of capillary trapping of gas clusters using X-ray microtomography
Author Geistlinger, H.; Mohammadian, S.; Schlueter, S.; Vogel, H.-J.
Source Titel Water Resources Research
Year 2014
Department BOPHY
Volume 50
Issue 5
Page From 4514
Page To 4529
Language englisch
Keywords gas clusters; capillary trapping; interfacial area
UFZ wide themes RU1
Abstract A major difficulty in modeling multiphase flow in porous media is the emergence of trapped phases. Our experiments demonstrate that gas can be trapped in either single-pores, multipores, or in large connected networks. These large connected clusters can comprise up to eight grain volumes and can contain up to 50% of the whole trapped gas volume. About 85% of the gas volume is trapped by multipore gas clusters. This variety of possible trapped gas clusters of different shape and volume will lead to a better process understanding of bubble-mediated mass transfer. Since multipore gas bubbles are in contact with the solid surface through ultrathin adsorbed water films the interfacial area between trapped gas clusters and intergranular capillary water is only about 80% of the total gas surface. We could derive a significant (R2 = 0.98) linear relationship between the gas-water-interface and gas saturation. We found no systematic dependency of the front velocity of the invading water phase in the velocity range from 0.1 to 0.6 cm/min corresponding to capillary numbers from 2 × 10−7 to 10−6. Our experimental results indicate that the capillary trapping mechanism is controlled by the local pore structure and local connectivity and not by thermodynamics, i.e., by the minimum of the Free Energy, at least in the considered velocity range. Consistent with this physical picture is our finding that the trapping frequency (= bubble-size distribution) reflects the pore size distribution for the whole range of pore radii, i.e., the capillary trapping process is determined by statistics and not by thermodynamics.
Persistent UFZ Identifier
Geistlinger, H., Mohammadian, S., Schlueter, S., Vogel, H.-J. (2014):
Quantification of capillary trapping of gas clusters using X-ray microtomography
Water Resour. Res. 50 (5), 4514 - 4529 10.1002/2013WR014657