The Relevance of Gas Hydrates

The main problem of hydrate formation will arise in pipelines transporting natural gas, because gas hydrates are solids and will leave deposits. The solid deposits reduce the effective diameter of the pipeline and can therefore restrict or even clog the flow properties. Furthermore, the formation of condensates, hydrates, or ice may occur in the course of decompression of natural gas stored in natural reservoirs (e.g., in salt caverns). The operation of oil and gas pipelines in the deep sea is significantly complicated by the formation of gas hydrates [1204]. Experience indicates that large gas hydrate plugs in gas and oil pipelines form most actively during the period of an unforeseen long shut-down. In static conditions, three types of hydrate crystals can be formed [1153]  

Surface-contact films and massive hydrates, which form by sorption of gas and water molecules on the surfaces of growing crystals 

Bulk diffusional whiskerlike hydrate, which forms both in the volume of gas and in the bulk of liquid water through sorption of molecules on the growing crystal surface and by tunnel sorption of molecules at the base of the crystal 

Gel-like soft crystals, which form in the bulk of liquid water at a defl-ciency of dissolved gas in water 

Under the appropriate pressure and temperature conditions for hydrate formation, there may be a simultaneous formation of some crystals and a decomposition of other crystals. 

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