SUBMARINE GAS-HYDRATE GENERATION FROM INFILTRATING GAS-SATURATED GROUNDWATER

Abstract

The temperatures and pressures under which gas hydrates may exist occur in areas with a thick permafrost layer and in most pelagic basins of the ocean. However, hydrates are not found in all zones where such conditions occur. It is usually assumed that hydrates are formed at depth from free gas (either trapped in pools or migrating) or from biogenetic gas generated in situ, or from dissolved gas in aquifers that have cooled for some reason. In this paper we attempt to demonstrate that infiltrating gas-containing groundwater plays a major role in gas-hydrate generation, particularly under submarine conditions. In principle, hydrates could also be formed from infiltrating gas-saturated waters on land, in shelf zones, and in areas covered by a thick frozen rock layer. But the process is unlikely to occur extensively in such zones: cryogenic cooling of artesian systems reduces formation pressures to the point at which the head for lifting the water from the depths to the surface is too low.