Methane hydrates: Across the Earth
Deep continental slopes, not the Arctic, hold most
What this tab covers How the resource varies with latitude, climate, terrain and geology: the richest and poorest regions and the leading countries.Nearly all hydrate lies in deep-marine sediments on continental margins. Only about 1% is associated with Arctic permafrost, though the permafrost deposits are the easiest to test.
Hydrate needs a supply of methane plus cold and pressure. It therefore occurs on continental slopes and rises in water deeper than about 300 to 500 m at all latitudes, and onshore and on shelves in the Arctic, where permafrost keeps sediments cold. Sand-rich deposits along margins with large river systems are the best prospects.
Rich and poor regions
| Region | Resource | Level |
|---|---|---|
| Deep marine sediments (global) | about 1,717 Gt of carbon, 95.3% of the inventory4 | high |
| Upper continental slopes (global) | about 63 Gt of carbon, 3.5%4 | medium |
| Permafrost-associated, onshore (global) | about 20 Gt of carbon, 1.11%4 | low |
| Alaska North Slope (US) | 53.8 tcf technically recoverable8 | medium |
| South China Sea, Shenhu area (China) | test well in 1,225 m of water; 861,400 cubic metres produced in 20209 | medium |
| Offshore India (NGHP-01 expedition) | 21 drill sites, 15 of them in the Krishna-Godavari basin9 | medium |
Largest cumulative gas volumes from offshore hydrate production tests 2020 9
| Country | cubic metres of gas |
|---|---|
| China (Shenhu, 2020, 30 days) | 861,400 |
| China (Shenhu, 2017, 60 days) | over 309,000 |
| Japan (Nankai Trough, 2017, second well, 24 days) | about 200,000 |
| Japan (Nankai Trough, 2013, 6 days) | about 119,500 |
Japan, China, India and the US run the most advanced national research programmes, and Japan and China have carried out the offshore production tests. Early US work estimated a mean of about 9,000 tcm of gas in place in US territory alone (1995), more than the whole recent global estimate of about 3,300 tcm, which shows how far assessments have come down.