OS4C-2：DESIGN OPTIONS FOR AVOIDING HYDRATES IN DEEP OFFSHORE PRODUCTION

Carlos A.B.R. CARDOSO1，Marcelo A.L. GONÇALVES2, Ricardo M.T. CAMARGO1
1. PETROBRAS – E&P, BRAZIL; 2. PETROBRAS , BRAZIL

    Hydrate blockage in subsea production systems is responsible for a significant portion of production losses from oil fields located under deep water depths. This problem tends to worsen in fields with more favorable conditions for hydrate blockage. This is the case of the fields recently discovered in Brazilian Pre-salt layer due to greater water depth, higher pressure, lower temperature and oil more prone to agglomeration. Additionally, in this scenario the logistic for hydrate removing, if a rig is required, is more complex due to the greater distance from shore. The overall conditions found in Brazil offshore fields prior to Pre-salt development allowed applying a less conservative hydrate prevention design when compared to other areas throughout the world. Now, while the global trend is to reduce the safety margin to manage hydrate risk rather than simply avoid them, Pre-salt layer players in Brazil are contemplating the possibility of increasing the robustness of their Flow Assurance design. This paper presents some suggestions in order to meet this goal.

    Among the proposals presented in this paper it can be highlighted: increased no-touch time, riser base gas lift and installation of subsea system access through hot stabs. The experience obtained in the operation of different offshore production platform shows that some existing topsides facilities make it easier to prevent and remove hydrate blockage. Some of these facilities are also discussed here.