The quantification of the interfacial area between fluids in a multiphase system in porous media has been a subject of growing interest in disciplines where mass transfer across fluid interfaces is of importance. In this study, a proof of concept for a novel kinetic interface sensitive (KIS) tracer is provided by employing a simple, low-cost, well-controlled dynamic column experiment in conjunction with a macroscale two-phase flow reactive transport model. The steel column is filled with a well-characterized porous medium consisting of well-sorted normally distributed glass beads (d 50 = 240 μm). KIS tracers were designed to determine the specific interfacial area, a wn , between a nonwetting fluid and a wetting fluid, by evaluating the chemical reaction rates and mass transfer across the fluid-fluid interface. This study shows for the first time a general framework behind the use of KIS tracers and their potential in assessing the a wn for a known capillary pressure-saturation relationship under laboratory conditions. A two-phase flow four-component reactive transport and a two-phase flow two-component transport numerical model were developed to simulate the oil flooding of the initially water saturated column and tracer breakthrough curves obtained from experimental data. These breakthrough curves were subsequently used to approximate a wn using a polynomial relationship. The interpretation of the KIS tracer column experiments indicates that the range for maximum value of a wn is between 500 and 540 m 2 /m 3 . The results also show that despite the use of two independently synthesized tracers, if the reaction kinetics are well quantified, similar a wn values can be obtained.

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Abstract. Hydrothermal quartz crystals, which occur in the Rusey Fault Zone (Cornwall, UK), show feathery textures and network-like filamentous textures. Optical hot-cathodoluminescence (CL) analysis and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) investigations on quartz samples revealed that positions exhibiting feathery textures (violet luminescence) contain higher amounts of Al and Li than quartz positions without feathery textures (blue luminescence), while concentrations of Al and Li are significantly lower in feathery textures. Both Al and Li correlate negatively with Si. Raman spectroscopy investigations revealed the presence of a weak peak at 507–509 cm−1 in quartz affected by feathery textures, which we attribute to the presence of  ≤  5 % moganite, a microcrystalline silica polymorph, intergrown with chalcedony. The combined occurrence of feathery textures and network-like filamentous textures in quartz samples from the Rusey Fault Zone points to the presence of a metastable silica precursor (i.e., amorphous silica or silica gel) before or during the crystallization.

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