Gas hydrates in nature and in the laboratory: necessary requirements for formation and properties of the resulting hydrate phase

Abstract Clathrate hydrates—also known as gas hydrates—are ice-like compounds consisting of and water molecules. They occur wherever elevated pressures low temperatures prevail; where enough hydrate-forming molecules are available. Therefore, natural hydrates at all active passive continental margins, in permafrost regions, some deep lakes, under unfavorable circumstances, also, pipelines. This article provides an overview the (thermodynamic) requirements various models for nucleation growth different hydrate structures that may which have been detected nature. Furthermore, this study also shows influence properties enclosed such size shape on structure thermodynamic resulting phase. Finally, complexity a environment with regard to influences sediments, microbial activity, salinity pore fluid formation is discussed.