(352h) Flowloop Investigations Towards Gas Hydrate Slurry Transportability

Gas hydrate blockages are often considered the major flow assurance problem during oil and gas production and transportation, mainly because of the fast timescales at which they can form, compared to other flowline solids. Understanding the gas hydrate slurry formation processes and flow properties are important to developing advanced strategies to manage gas hydrate formation in subsea flowlines, as well as other technological applications of gas hydrates. In this paper we present the key lessons learned from flowloop investigations of gas hydrate mitigation strategies in partially dispersed systems. These systems are often considered the most challenging when assessing the risks due to hydrate plug formation. The mitigation strategy of the addition of an anti-agglomerant on partially dispersed systems, based on quaternary ammonium salts, is used to facilitate hydrate slurry flow over a range of conditions, including different water content and mixture velocity. Continuous pumping as well as transient conditions of shut-in (several hours without pumping) and restart (resuming pumping) were applied. The latter transient operations are often very challenging for sustained flow assurance in subsea flowlines. The results from these tests indicate that an anti-agglomerant could be utilized to maintain hydrate slurry transport at low to mid water contents, but high pressure drops can be encountered for higher water content systems.