Gas hydrate risks minimization in deepsea hydrocarbon flowlines, especially in high water to oil ratios, and is critical for the oil and gas flow assurance industry. Although there are several reviews on gas hydrate mitigation in gas-dominated systems, limited reviews have been dedicated to the understanding and mechanism of hydrate formation and mitigation in oil-dominated systems. Hence, this review article discusses and summarizes the prior studies on the hydrate formation behavior and mitigation in oil-dominated multiphase systems. The factors (such as oil volume or water cut, bubble point, and hydrate formers) that affect hydrate formation in oil systems are also discussed in detail. Furthermore, insight into the hydrate mitigation and mechanism in oil systems is also presented in this review. Also, a detailed table on the various studied hydrate tests in oil systems, including the experimental methods, inhibitor type, conventions, and testing conditions, is provided in this work. The findings presented in this work are relevant for developing the best solution to manage hydrate formation in oil-dominated systems for the oil and gas industry.

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Amino acids are known as novel kinetic hydrate inhibitor (KHI) for hydrate mitigation, however, the performance in oil system is not well justified up to date. In this study, the kinetics of methane hydrates in oil dominated systems using valine amino acid has been studied in a high-pressure gas hydrate reactor at 80 bar and 1 °C using the constant cooling method. Drilling oil was used in this work to mimic the oil phase in flow assurance. The results shows that valine delays hydrate formation nucleation time 4 times compared with pure water systems. This finding is contrary to most claims in literature that shows that valine promotes hydrate in gas dominated system. However, the inhibition impact of valine exhibited in this work might be due to the presence of oil with is absence in the most literature studies. The findings in the work are useful for hydrate mitigation using amino acids in flow assurance.