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Abstract

For practical purposes, kinetic hydrate inhibitors must perform in a predictable manner in the field. However, the complexity of the petroleum fluid composition, the presence of dissolved electrolytes, and high driving force (overpressure or sub-cooling), make it difficult to impossible task to achieve. In this thesis, the performance of two chemical kinetic inhibitors, polyvinylcaprolactam (PVCap) and polyvinylpyrrolidone (PVP), and two biological ones, type I and III antifreeze proteins (AFP I and III) were evaluated under conditions mimicking oil and gas filed ones. The evaluation was done by using a double high pressure stirred vessel (crystallizer), a high-pressure cell in conjunction with a rotational rheometer and a high pressure micro differential scanning calorimeter. Although the above noted inhibitors were found to prolong the hydrate induction time and reduce the initial hydrate growth in saline solutions, the rate was found to increase when hydrate crystals started to form in the gas phase of the crystallizer. Circular dichroism experiments suggested that the saline solution does not perturb the structure of AFP I and III. However, in the presence of NaCl, the inhibitory activity of AFP I to prolong induction time decreased while AFP III was more active. Here, increase in induction time was ordered: no inhibitor