Natural gas hydrates – Insights into a paradigm-shifting energy resource

Experts have identified natural gas hydrates, which are found in the shallow seabed and beneath permafrost regions, as an energy source (mostly methane) that is greener than other petroleum fuel resources. With their worldwide distribution and abundance, gas hydrates have vast potential to become the next pillar of the energy industry. Although no entity has established methane extraction from hydrates at a commercial scale yet, extensive laboratory experiments have introduced several extraction strategies. Methods such as depressurization, thermal stimulation, and inhibitor injection are likely to disturb seabed integrity, which may result in catastrophic consequences. However, the CO2 replacement method is inferred to be preserving the seabed stability, offering an opportunity to reduce anthropogenic CO2 emissions safely. In this paper, we provide a comprehensive review of the progress of experimental work in developing methane-extraction methods for gas hydrate reservoirs. Depressurization combined with thermal stimulation can be proposed as a viable methane extraction method based on laboratory-scale experiments, however, a sustainable extraction method is yet to be developed to field-scale when both economic and environmental perspectives are considered. A handful of field production runs have delivered positive outcomes to establish the exploitability of natural hydrate reservoirs, but thorough investigations and scientific collaborations are needed to develop hydrate accumulations as a commercially viable energy source. © 2022