4. Methane hydrate gas resources

Since the early 1970s, global estimates of the volume of methane contained in hydrates have been published.

In the first assessment, which assumed that all sediments within the hydrate stability zone would contain hydrate, the estimate reached the astronomical figure of 1.9 × 10 ¹⁸ m ³ of methane. This estimate, which was made even before the first hydrate samples were collected from marine sediments, was quickly revised downwards.

Over the following decades, despite advances in our knowledge of continental margins and our understanding of hydrate formation from biogenic or thermogenic methane, estimates remain subject to very high uncertainties, due to the great heterogeneity of hydrate distribution in sediments. The latest estimates of in-place...