Investigation of Potential Hydrate Problems in Case of Interrupted MEG Injection in the 32b Sealine From Offshore to South Pars Gas Treating Plant Phases 2 and 3 Using OLGA2000

摘要

Phases 2 and 3 comprise of two 1000 MMSCFD wellhead platforms, two multi-phase (Gas / Condensate / Glycolated Water) 32" pipelines and two onshore gas treating plants. Gas is not dehydrated offshore. Only glycol (MEG) and additives are injected in the sealines for hydrate formation prevention. The length of each pipeline is approximately 109 km. OLGA2000 is used to manage the operating conditions and to issue the operating guidelines for the pipeline. The hydrate formation curve of the raw gas has been calculated with PROII. The operating conditions along the sealine (T and P) have been extracted from OLGA2000 simulations. The combination of the hydrate formation curve and the operating conditions graph yields to estimate the location where the risk of hydrate formation starts to appear when no hydrate inhibitor is injected. The results of the simulations show that a hydrate formation risk will occur approximately 8 hours after stop of MEG injection. It is found that steady-state MEG injection at a rate of 5 m3/h is sufficient for complete hydrate protection of the sealine under winter conditions. The resulting inlet concentration is 30-35%.