Institute of Petroleum Engineering

Centre for Gas Hydrate Research Publications

Abstract 029
Gas Hydrates - Implications on the Petroleum Industry
Østergaard, K.K., Tohidi, B., Danesh, A., Todd, A.C.
EAGE 5th Annual Research Review, Edinburgh, 19 February (1997).
Gas hydrates have been known since 1810 when they were discovered by Sir Humphrey Davy. Sir Davy observed that a solid could be formed when an aqueous solution of chlorine was cooled to below 9°C. For many years the discovery of this reaction, by which a combination of gas and water lead to the formation of a solid phase, was considered as a scientific curiosity. In 1934, Hammerschmidt found that the plugging of gas transmission lines was caused by the formation of gas hydrates and not, as believed earlier, by the formation of ice. Efforts were made on reducing the hydrate problems by adding hydrate inhibitors. Today, adding methanol is still the most common way of preventing plugging of transfer lines prone to hydrate formation. However, in resent years, research on so-called kinetic inhibitors has attracted considerably attention. The perception of gas hydrates being a man-made substance, either in pipelines or in the laboratories, lasted until the 1960s when huge amounts of hydrates were found in both deep ocean sediments and permafrost regions. Today it is estimated that natural occurrences of gas hydrates contain about twice the amount of energy than all the fossil fuel reserves. Some other interesting areas which have become subject for hydrate research are the potential of using gas hydrates as transport media, in separation processes and the relevance to climate changes. The discovery of the Heavy Hydrate Formers also attracted considerable resources. Until the late 1980s, only molecules smaller than n-butane were considered as potential hydrate formers. Possible structures were structure I and structure II. The discovery of structure H by Ripmeester et al. in 1987 changed the picture as molecules as large as methylcyclohexane now became possible guests. This, together with larger guests reported for structure II renewed the focus on hydrates with emphasis on the problems for natural gas and condensate systems.