A combination of low temperature, high pressure and presence of water and natural gases provides the ideal conditions for formation of gas hydrates. Gas hydrates may precipitate in pipes and production gear during recovery and transportation of oil and gas resulting in production stops implying major economical losses. Presently large quantities of thermodynamic inhibitors, mainly methanol or glycol, are utilized to inhibit gas hydrate formation. Large amounts of thermodynamic inhibitor are required to prevent hydrate formation (up to 50% of the aqueous phase)
Alternatively it is possible to control formation of gas hydrates using small amounts of polymeric compounds; so-called kinetic inhibitors (KHIs), which instead of inhibiting the formation thermodynamically, work by slowing the formation rate of hydrates. Although using kinetic inhibition offers several advantages over thermodynamic inhibition, such as low chemical usage and savings in operational and capital expenditures, their implementation in field operations has been limited due especially to environmental restrictions as a result of their poor biodegradability.
We have tested the efficacy of antifreeze proteins, from fish and insects, as kinetic gas hydrate inhibitors. Especially antifreeze proteins from the Danish bark beetle have been shown to be particularly effective. These proteins have the greatest thermal hysteresis (difference between melting and freezing point of ice) of any known antifreeze protein, and initial results indicate they are astonishingly good hydrate inhibitors.
In this work we present results of kinetic inhibition tests of these proteins compared with other antifreeze proteins and commercially available kinetic inhibitors. Strategies for improvement of the inhibitors are presented in the framework of a larger project.