Use of Low-Dosage Hydrate Inhibitors in Sour Systems

Low-dosage hydrate inhibitors (LDHIs) continue to gain acceptance as alternatives to traditional hydrate control techniques. While these products have been in use for numerous years, there have been few reports of the use of LDHIs in sour systems. Hydrogen sulfide (H₂S) has long been known to affect the conditions at which hydrates become stable. Often, the presence of percent levels of H₂S significantly increases the temperature at which hydrates can form in hydrocarbon production and transmission systems compared to the corresponding sweet system. Many questions have been raised as to whether the presence of H₂S affects the performance of LDHIs. While LDHI performance tests in sweet systems have become routine, it is very difficult to test LDHI performance in the presence of significant H₂ S. Despite the difficulties in studying LDHIs in sour systems in the laboratory or pilot scale tests, several field applications of LDHIs have been conducted over the last several years. This paper will detail five case histories of successful field applications of both kinetic hydrate inhibitors (KHIs) and anti-agglomerants (AAs) in sour systems. The results show that LDHIs can indeed be used effectively to control hydrates in sour systems.