Nucleation probability and memory effect of methane-propane mixed gas hydrate

To improve the understanding on methane storage in wet porous media under hydrate favorable conditions, hydrate formation loaded by an activated carbon bed in three three-dimensional printed containers was carried out, while the recycling performance of the activated carbon bed was also evaluated. As expected, due to low permeability of the bed, poor hydrate kinetics was observed for small particles, but this is improved by increasing the exposure of the bed. When there is hydrate formation loaded by an activated carbon bed in a container, the specific contact area governs hydrate nucleation and growth kinetics, and the accessibility of methane with inner water increases with the increase in gas–solid contact area, giving rise to fast hydrate nucleation and large methane uptake. Impressively, the hydrate induction time for container 3 is only 3.53 and 41.79% of that in container 1 under the filling ratios (volume ratio of the sample to container) of 80 and 100% separately, while the methane uptake increases by about 8% for both the scenarios. In addition, because of the migration of water to side walls, exceptional recycling performance of the activated carbon bed was also observed, and this characteristic causes the bed to be easily charged and discharged like a battery. These findings may pave the way for the application of the adsorbed natural gas technology using wet activated carbon under hydrate-favorable conditions.

Section: Resultsmentioning

confidence: 88%

Hydrate Formation Loaded by an Activated Carbon Bed in 3D-Printed Containers

Zhang

Wang

2021

“…Due to the difficulty of directly observing the process of hydrate generation from nanobubbles, most of the current research utilize molecular dynamics simulations. Hydrates are considered to be first generated at the nanobubble gas−liquid interface, where high-pressure guest molecules and dipole layer structures that promote nucleation are present, 39 as shown in Figure 5b. The above results suggest that nanobubbles can promote the nucleation of hydrates.…”

Section: Comparison Of the Nanobubbles Generated Bymentioning

confidence: 99%

Probing the Effects of Ultrasound-Generated Nanobubbles on Hydrate Nucleation: Implications for the Memory Effect

Liu

et al. 2023

Understanding the microscopic hydrate phase transition process is of crucial importance to the application of hydrate-based techniques. This process is nevertheless significantly limited by the insufficient enrichment of hydrophobic gas molecules in the solution. Here, in this work, ultrasonic technology was applied to generate stable and large amount of nanobubbles in pure water to promote hydrate formation kinetics. The particle size distribution of the nanobubbles was following the log-normal distribution, with a concentration of ∼10 9 mL −1 and a diameter concentrated in 100−120 nm. The concentration of the nanobubbles increased with the ultrasonic duration and power. Notably, the concentrations of nanobubbles produced by hydrate decomposition were slightly higher with the bubble size concentrated around 200 nm. The effect of nanobubbles on the induction time of hydrate formation was further analyzed by forming from the nanobubble solution with different concentrations and particle size distributions. Hydrate formation induction time was reduced by up to 61.13%. We further analyzed the mechanism of the nanobubble dominant hydrate memory effect. The results proved ultrasound as an approach to enhance the solubility of gases in water and thus promote hydrate formation kinetics, providing evidence for the dominant role of nanobubbles in the memory effect.

“…Hydrate reformation is common during NGH exploitation due to the memory effect. − The secondary hydrate-induced plugging of sand-control media was comprehensively discussed by Li et al The experimental result revealed that hydrate reformation within sand screens would cause permeability loss of up to 98%, which would severely affect gas productivity. During hydrate clogging, the permeability of the screen shows dual-gradient decreasing characteristics (see Figure ).…”

Section: Recent Advances In Sand Control Systemmentioning

confidence: 99%

Sand Production Management during Marine Natural Gas Hydrate Exploitation: Review and an Innovative Solution

Chen

et al. 2021

Self Cite

Natural gas hydrate (NGH) is widely distributed worldwide with great reserves and is generally accepted as a promising alternative energy source. However, sustainable, efficient, and safe NGH development has been proven to be restricted by a series of geomechanical problems, among which sand production has become prominent and attention-catching. This review systematically summarizes the up-to-date literatures and reports our latest work to improve the fundamental understandings of the sand production issues in NGH development. It is noted that sand production is defined as a systematic “issue”, rather than a “problem” in this paper, considering both the adverse and favorable influences of sand production on continuous gas production from hydrate-bearing sediment (HBS). Several challenges and insightful suggestions are put forward for future research from the viewpoint of the sand production management system (SMS). Furthermore, an innovative method for unlocking conflicts between sand production and gas extraction in muddy HBS is proposed, namely, the gravel-huff to clay-puff replacement (GCR) technique. The outlook and perspectives of this technique are presented, as well as the key challenges to be resolved.