Class of Kinetic Hydrate Inhibitors with Good Biodegradability

Abstract

Kinetic hydrate inhibitors have been used successfully in the field for about the last 13 years to prevent gas hydrate formation mostly in gas- and oilfield production lines. They work by delaying the nucleation and often also the growth of gas hydrate crystals for periods of time dependent upon the subcooling in the system. Current commercial kinetic hydrate inhibitors are used for field applications where the subcooling is as high as about 10 °C. In the Norwegian sector of the North Sea, very few of the commercial kinetic hydrate inhibitors are available for use offshore because of poor environmental properties usually related to biodegradability. We have designed and synthesized a class of kinetic hydrate inhibitor, which appears to show good biodegradability (OECD306, >20% in 28 days). Inhibitor performance tests have been carried out in stirred autoclaves (titanium and sapphire) using a natural gas blend and saline water giving structure II hydrates. In the presence of solvents, we have obtained a fairly good performance of the new inhibitors but a little lower than that of a current commercial inhibitor Luvicap 55W.