Formation, growth and ageing of clathrate hydrate crystals in a porous medium

Abstract

An experimental study was performed to visually observe the driving force dependence of hydrate growth in a porous medium filled with either liquid water and dissolved CO 2 or liquid water and gaseous CO 2 . The given system subcooling, ÁT sub , i.e. the deficiency of the system temperature from the triple CO 2 ÀhydrateÀwater equilibrium temperature under a given pressure, ranged from 1.7 K to 7.3 K. The fine dendrites initially formed at ÁT sub ¼ 7.3 K changed quickly into particulate crystals. For ÁT sub ¼ 1.7 K, faceted hydrate crystals grew and the subsequent morphological change was hardly identified for an eight-day observation period. These results indicate that the physical bonding between hydrate crystals and skeletal materials becomes stronger with decreasing driving force, suggesting that the fluid dynamic and mechanical properties of hydratebearing sediments vary depending on the hydrate crystal growth process.

Examination of Hydrate Formation Methods: Trying to Create Representative Samples

“…The seemingly contradicting results-formation of additional hydrate and decreasing seismic velocities (i.e., cementation between sediment grains)-are attributed to the migration of hydrate crystals from intergranular contacts to the pore fluid. This explanation is supported by the observation by Katsuki et al (2006Katsuki et al ( , 2007. Using glass micromodels, they showed that when water-saturated, gas hydrates (methane hydrate and CO 2 hydrate) change their habit within the pore space over time.…”

Heat Transfer Analysis of Methane Hydrate Sediment Dissociation in a Closed Reactor by a Thermal Method

“…Then the methane was dried and charged into the reactor steadily until the pressure rose to the given pressure of 8.4 MP at 20.5 °C and the flow meter and PID system are used to measure and record the amount of methane gas during this process. Finally, the air bath system was turned on and the temperature kept at 1 °C which is higher than the ice point to avoid the formation of ice in order to remove the buffer effect which is observed by Pang et al [14,15]. The main materials used in the experiment are listed at Table 1.…”

“…A series of experimental studies were conducted on visual observation of the pore-scale dissociation of hydrate crystals caused by a temperature increase in a closed system and the mechanism of the dissociation of the methane hydrate crystals was discussed considering the heat and mass transfer of methane around the dissociating methane hydrate crystals. Their results demonstrate that the methane molecules released from these hydrate crystals were transferred through the liquid water phase to the methane gas slugs surrounding these hydrate crystals [15][16][17]. A new re-gasification system, in which warm water penetrates through a bed of gas hydrate pellets for the recovery of gas from stored hydrate, was investigated to achieve a more compact and more efficient re-gasification system by Tanaka et al [18,19].…”

X-ray CT Observations of Methane Hydrate Distribution Changes over Time in a Natural Sediment Core from the BPX-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well

“…The characteristic of hydrate redistribution has been observed at the grain scale in other experiments (Katsuki et al, 2005;Katsuki et al, 2006;Tohidi et al, 2001). When plunged into the hydrate stability zone, hydrate will first form at the methane-water interface, either as a film on a methane gas bubble or on the surface of water at the grain contacts.…”