Inhibition of Structure I and II Gas Hydrates using Synthetic and Biological Kinetic Inhibitors

Use of low-dosage hydrate inhibitors in oil and gas field applications has been limited mainly because there are uncertainties related to their efficiency in preventing hydrate formation or because of environmental restrictions. Another question that normally arises in connection with use of low-dosage hydrate inhibitors is how they interact with other (than water) compounds normally found in oil and gas production pipelines. In this work three different experimental approaches to obtain hydrate induction times have been tested for structure I and II hydrate. All experiments were conducted in a high-pressure stirred cell. The results suggest that by adding small amounts of impurities to the hydrate-forming system a significant improvement in the reproducibility of induction times can be obtained. Adding salt and heptane to the system (as a simple model for seawater and a light crude) was found to increase the hydrate formation rate. Ice-structuring protein type III identified in the ocean pout, a biological inhibitor, was added to the various hydrate-forming systems to investigate its potential as a low-dosage hydrate inhibitor. As a reference, polyvinylcaprolactam, a well-known and quite effective kinetic inhibitor was used. The ice-structuring protein was found to outperform polyvinylcaprolactam for both structure I and structure II hydrate, suggesting that ice-structuring proteins hold a promising potential as environmentally friendly kinetic hydrate inhibitors.