Successful cross-group and cross-project cooperation between SimTech, SFB 1313 and researchers from the Universities of Göttingen and Bochum

December 7, 2023

Researchers Holger Steeb, Holger Class, Rainer Helmig, and Nikolaos Karadimitriou who are at the same time highly involved in SimTech and SFB 1313 “Interface-Driven Multi-Field Processes in Porous Media – Flow, Transport and Deformation” have co-authored a new publication together with colleagues from the Universities of Göttingen and Bochum. The publication "Estimation of Capillary-Associated NAPL-Water Interfacial Areas for Unconsolidated Porous Media by Kinetic Interface Sensitive (KIS) Tracer Method", published in "Water Resources Research", is the result of a successful cross-group and cross-project collaboration between SimTech researchers from Project Network PN 1, SFB 1313 researchers from projects A02, C04 and Z02 as well as researchers from the Universities of Göttingen and Bochum.


By employing kinetic interface sensitive (KIS) tracers, we investigate three different types of glass-bead materials and three natural porous media systems to quantitatively characterize the influence of the porous-medium grain-, pore-size and texture on the specific capillary-associated interfacial area (FIFA) between an organic liquid and water. By interpreting the breakthrough curves (BTCs) of the reaction product of the KIS tracer hydrolysis, we obtain a relation for the specific IFA and wetting phase saturation. The immiscible displacement process coupled with the reactive tracer transport across the fluid–fluid interface is simulated with a Darcy-scale numerical model. Linear relations between the specific capillary-associated FIFA and the inverse mean grain diameter can be established for measurements with glass beads and natural soils. We find that the grain size has minimal effect on the capillary-associated FIFA for unconsolidated porous media formed by glass beads. Conversely, for unconsolidated porous media formed by natural soils, the capillary-associated FIFA linearly increases with the inverse mean grain diameter, and it is much larger than that from glass beads. This indicates that the surface roughness and the irregular shape of the grains can cause the capillary-associated FIFA to increase. The results are also compared with the data collected from literature, measured with high resolution microtomography and partitioning tracer methods. Our study considerably expands the applicability range of the KIS tracers and enhances the confidence in the robustness of the method.

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