The two‐phase flow IPTT method for measurement of nonwetting‐wetting liquid interfacial areas at higher nonwetting saturations in natural porous media

Abstract

Interfacial areas between nonwetting‐wetting (NW‐W) liquids in natural porous media were measured using a modified version of the interfacial partitioning tracer test (IPTT) method that employed simultaneous two‐phase flow conditions, which allowed measurement at NW saturations higher than trapped residual saturation. Measurements were conducted over a range of saturations for a well‐sorted quartz sand under three wetting scenarios of primary drainage (PD), secondary imbibition (SI), and secondary drainage (SD). Limited sets of experiments were also conducted for a model glass‐bead medium and for a soil. The measured interfacial areas were compared to interfacial areas measured using the standard IPTT method for liquid‐liquid systems, which employs residual NW saturations. In addition, the theoretical maximum interfacial areas estimated from the measured data are compared to specific solid surface areas measured with the N2/BET method and estimated based on geometrical calculations for smooth spheres. Interfacial areas increase linearly with decreasing W‐phase (water) saturation over the range of saturations employed. The maximum interfacial areas determined for the glass beads, which have no surface roughness, are 32 ± 4 and 36 ± 5 cm−1 for PD and SI cycles, respectively. The values are similar to the geometric specific solid surface area (31 ± 2 cm−1) and the N2/BET solid surface area (28 ± 2 cm−1). The maximum interfacial areas are 274 ± 38, 235 ± 27, and 581 ± 160 cm−1 for the sand for PD, SI, and SD cycles, respectively, and ∼7625 cm−1 for the soil for PD and SI. The maximum interfacial areas for the sand and soil are significantly larger than the estimated smooth‐sphere specific solid surface areas (107 ± 8 cm−1 and 152 ± 8 cm−1, respectively), but much smaller than the N2/BET solid surface area (1387 ± 92 cm−1 and 55224 cm−1, respectively). The NW‐W interfacial areas measured with the two‐phase flow method compare well to values measured using the standard IPTT method.

Pore‐Scale Modeling of Fluid‐Fluid Interfacial Area in Variably Saturated Porous Media Containing Microscale Surface Roughness

“…Larger X values produce larger interfacial areas for a given set of conditions, as a larger X represents a larger specific solid surface area due to greater magnitude of surface roughness. These results are consistent with prior experiment-based studies that have reported larger interfacial areas for media with greater surface roughness (Costanza & Brusseau, 2000;Costanza-Robinson & Brusseau, 2002;Peng & Brusseau, 2005;Brusseau et al, 2008Brusseau et al, , 2010Brusseau et al, , 2015Zhong et al, 2016).…”

“…As expected, decreasing L m increases SA due to smaller grain size (and smaller pore size), which results in larger A nw for the full-range of saturations. These results are consistent with prior experiment-and model-based studies that have reported larger interfacial areas for media with smaller grain diameters (Cary, 1994;Anwar et al, 2000;Costanza & Brusseau, 2000;Costanza-Robinson & Brusseau, 2002;Cho & Annable, 2005;Dobson et al, 2006;Brusseau et al, 2008Brusseau et al, , 2009Brusseau et al, , 2010Costanza-Robinson et al, 2008;Zhong et al, 2016). The relative impact of surface roughness on A nw is greater for smaller L m , as illustrated by comparing the two sets of simulations for X = 1 and X = 50 for L m = 10 vs. 160 μm (Figure 6b).…”

Assessing XMT‐Measurement Variability of Air‐Water Interfacial Areas in Natural Porous Media

“…Additionally, Narter and Brusseau independently determined A max from interfacial partitioning tracer test measurements, and the resultant value (28 cm −1 ) was consistent with the XMT-based A max as well as the SSSA-NBET and GSSA. Zhong et al (2016) used a two-phase flow interfacial partitioning tracer test method to measure organic liquid-water interfacial areas for the same glass beads, and the A max (34 cm −1 ) is comparable to the values above. Finally, Lyu et al (2017) used the gas-absorption/chemical reaction method to measure air-water interfacial areas for the same glass beads.…”

The Gas‐Absorption/Chemical‐Reaction Method for Measuring Air‐Water Interfacial Area in Natural Porous Media

“…The significance of fluid‐fluid interfacial area for porous‐media systems has fomented the development and application of methods for its characterization and quantification. The methods available to measure fluid‐fluid interfacial area in natural porous media include mass‐balance tracer tests (Anwar, ; Anwar et al, ; Araujo et al, ; Karkare & Fort, ; Schaefer et al, ), aqueous and gas‐phase interfacial partitioning tracer tests (Brusseau et al, ; Cho & Annable, ; Costanza‐Robinson & Brusseau, ; Dobson et al, ; Jain et al, ; Kim et al, ; McDonald et al, ; Narter & Brusseau, ; Peng & Brusseau, ; Saripalli et al, ; Zhong et al, ), and pore‐scale imaging (Al‐Raoush, ; Al‐Raoush & Willson, ; Brusseau et al, ; Costanza‐Robinson et al, ; Culligan et al, ; Ghosh & Tick, ; McDonald et al, ; Porter et al, ; Prodanovic et al, ; Schnaar & Brusseau, ). Each method has associated limitations that can constrain their use.…”