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%.
The SOUTH PARS field process facilities have been developed on the basis of a "wet" process scheme, which involves minimum offshore processing. The reservoir fluid is collected on Wellhead platform and routed without any treatment via multiphase sealine to shore where it is processed to deliver gas and condensate at specifications. Each wellhead platforms has a capacity of 1000 MMSCFD of gas and 40 bbl/day of condensate.
The wellhead fluid is assumed to be water saturated at reservoir conditions. The BUKACEK correlation is used for water saturation of the reservoir fluid. At the reservoir conditions the saturated water is 930.96 BBL/D. This water will condense in the sealine between the wellhead platform and the onshore plant. MEG (Mono Ethylene Glycol) is therefore injected at platform departure to prevent both hydrate formation and corrosion in the sealine.
Hydrate formation curve of each gas depends on the composition of the fluid. Adding methanol or glycol lead to a depression of the hydrate formation temperature.
