Hydrate blockage in subsea oil/gas flowlines: Prediction, prevention, and remediation

With the development of oil and gas resources moving from onshore to offshore, hydrate blockage issues in subsea flowlines have become increasingly prominent. Hydrate control methods are critical and could be created from prediction, prevention, and remediation. The industrial strategy has gradually shifted from traditional complete avoidance to risk management in the past two decades. Hydrate blockage prediction simulators are reviewed in detail as a promising risk management method. The key factors for blockage prediction include formation/blockage mechanism, growth rate, hydrate amount, and slurry viscosity. The anti-hydrate surface, a potential prevention method, is discussed from the perspectives of "hard to form, weak to deposit, easy to remove" for hydrate. The remediation methods of inhibitor injection, depressurization, thermal methods, and decomposition models for developing safety simulators are summarized. In conclusion, hydrate blockage prediction simulators and anti-hydrate surfaces show good application potential. A remediation safety simulator is also necessary for determining decomposition pressure. By checking the main features of all the models, weak applicability owing to empirical parameters is the primary problem. Although surface modification studies have progressed, systematic analyses have not been conducted sufficiently. Future efforts should be devoted to improving the applicability of the models by developing dimensionless parameters, as well as systematically studying and designing for surface chemical and physical properties.