Phase Equilibrium of Methane Hydrate in Sediments: Experimental and Theoretical Characterization

Abstract

A series of phase equilibrium tests were performed to explore the influence of various experimental conditions, including initial water content, dry density, and salt content, on the phase equilibrium behavior of methane hydrate in fine- and coarse-grained sediments. The results indicate that the phase equilibrium condition of pore hydrate is significantly influenced by the adopted experimental conditions and the sediment types. It is shown that in equilibrium, a unique relationship (the soil hydration characteristic curve (SHCC)) exists among the temperature shift, the unhydrated water, and the amount of dissolved salt. Under salt-free conditions, the SHCC is independent of dry density for coarse-grained specimens, whereas it is slightly influenced by the dry density for fine-grained specimens. A recently developed phase equilibrium model of pore hydrate, which can account for osmotic, capillary, and adsorptive effects, is introduced to interpret the experimental results. It is shown that the SHCC of the coarse-grained specimens can be very well described by the model; for fine-grained specimens, however, the effect of salt content on matric suction has to be taken into account in the model prediction.

Affecting Mechanism of Natural Sandstone Porous Media on the Formation and Phase Equilibrium of Methane Hydrate

“…The influence of porous media on hydrate phase equilibrium has been extensively studied in the field of gas hydrates. − The pore structure inside the porous media can affect the heat and mass transfer of the internal gas and liquid and, thus, affect the phase equilibrium conditions of hydrates . Early studies on porous media were mainly focused on simulating the natural gas occurrence environment under natural conditions to obtain a deeper understanding of the effect of porous media on the process of hydrate formation, and the main materials were usually focused on silica sand , and clay. , As research has progressed, it has been observed that porous media, including activated carbon, glass beads, carbon nanotubes, and nanomaterials, are commonly employed to enhance the formation of hydrates.…”

The ex situ exsolved Ni–Ru alloy from nickel–ruthenium co-doped SrFeO3−δ perovskite as a potential catalyst for CC and CO hydrogenation

“…Literature survey reveals that the substitution of a small quantity of Ni to SrFeO 3−d has been reported to yield positive outcomes in terms of chemical looping and dry reforming of methane. 17 Furthermore, the introduction of two distinct ions at the B site through doping has been found to enhance the activity even further, resulting in synergistic effects. This approach serves as a remarkable catalyst design strategy.…”