温暖化防止のためのCCS

[1101-04-01] Micro-tomographic analysis of pores and trapped phase in various unconsolidated porous media

○Patmonoaji Anindityo¹, Kento Tsuji¹, Tetsuya Suekane¹ (1. Tokyo Institute of Technology)

司会：末包 哲也（東京工業大学）

Keywords:Microtomography, Pore Size, Bubble Size, Bubble Shape, Interfacial Area

Mass transfer of trapped phase to mobile phase inside a porous medium is an important phenomenon in contaminant　transport, in-situ bioremediation, and geological carbon sequestration. One of parameter that affects mass transfer is specific interfacial area of trapped phase. This parameter is determined by the trapped phase shape and size distribution, which is affected by the pore size distribution (PSD). Furthermore, PSD is affected by the particle of porous media.We assembled porous media from various particles shape and size and measured the PSD, porosity, trapped phase shape and size distribution, and trapped phase saturation and interfacial area by using CT X-ray microtomography. All of the porous media were assembled in cylindrical container, and the particle was poured into it under vibration resembling the close random　packing. Glass beads (GB), Toyoura sands (TS), and plastic beads (PB), which respectively corresponds to water wet spherical shape to angular shape particle, were used as particles. For fluid pairs, nitrogen and water were used as the trapped and mobile phase.By dividing the PSD with the particle mean size (d₅₀), sphere particle indicates larger pore size although it generates lower porosity. Normalizing the PSDs with the pore median size (d_p,median) show that all PSDs fall to the same Gaussian function suggesting proportional variance. Also, distribution of trapped phase indicates that the capillary trapping is not governed by minimum free Gibbs energy (thermodynamics filling) but by statistical events. The trapped phase shape follows two kinds of function, which are single-pore and multi-pores. For the trapped phase amount, angular particles generate more amount than angular particles. GB and TS generates similar interfacial area but lower than PB. By normalizing the specific interfacial area, each particle types tends to fall in the same line disregarding the particle size suggesting proportionality.