Crystalline structures of water that surround low molecular weight gases present in crude oil

Gas hydrates occur abundantly in nature, both in Arctic regions and in marine sediments. Gas hydrate is a crystalline solid consisting of gas molecules, usually methane, each surrounded by a cage of water molecules. It looks very much like water ice. Methane hydrate is stable in ocean floor sediments at water depths greater than 300 metres, and where it occurs, it is known to cement loose sediments in a surface layer several hundred meters thick. (source: US Geological Survey)