Journal of Chemical and Engineering Data, Vol.60, No.2, 293-298, 2015
Effectiveness of Low-Dosage Hydrate Inhibitors and their Rheological Behavior for Gas Condensate/Water Systems
Management of hydrate flow assurance issues has been a major problem in offshore and deepwater-oil and gas production. Hydrate flow assurance strategies include the use of low dosage hydrate inhibitors (LDHIs) such as kinetic hydrate inhibitors (KHIs) and antiagglomerants (AAs) among others. The effectiveness of AAs should be studied in detail before embarking on using such chemicals in the field. In the current work, a systematic AA laboratory screening study has been undertaken on a gas condensate field. The rheological measurement of hydrate slurry in the presence of AAs under various operating conditions provided important insight into AA screening. Hydrate slurries were formed in a fully visual sapphire pressure-volume-temperature (PVT) cell in the presence of various AA chemicals. The hydrate slurry was then transferred to a high pressure rheometer for viscosity measurements at various shear rates. The effectiveness of these chemicals and their rheological behavior were evaluated as a function of pressure, water cut, and shear rates under various operating scenarios, that is, flowing conditions and shutdown/restart conditions. The result of this hydrate flow assurance testing indicated that hydrate slurry in the presence of the AAs behaved as a non-Newtonian fluid with a shear thinning effect. The water cut and pressure had an impact on the effectiveness of the AAs.