The development strategy of a deepwater project often implies a core area to be developed as soon as the first exploration results indicate an amount of reserves that sustains a standalone floating production facility, which can accommodate production start-up while further exploration activities focus on other leads/reservoirs in the area, to be developed as tieback of satellite fields for production extension.
Angola West Hub is emblematic of such development strategy which turns into a complex and technology driven project, envisaging deepwater long tiebacks and demanding technical solutions supporting flow assurance, thermal management and reservoir productivity.
West Hub is located in the Angolan deep offshore Block 15/06, approximately 130 km West of Soyo, with a water depth ranging between 1200 m and 1500 m. The project includes three subsea fields: Sangos, Cinguvu and Mpungi, to be tied to a dedicated production hub, namely N'goma FPSO, through a phased development campaign. Production start-up and ramp-up are based on Sangos and Cinguvu, which are between 5 and 7 km far from the FPSO. Production is then sustained through the tieback of Mpungi, which is located 15÷18 km North East of N'goma FPSO.
Resevoir productivity is optimized through many advanced technical solutions:
a dedicated gas network provides bottom-hole gas lift to both Sangos and Cinguvu;
a water alternate gas system (WAG) serves Sangos field;
a complex subsea water injection network supplies both Cinguvu and Mpungi
Riser-base gas lift and subsea multiphase boosting optimize Mpungi production and final oil recovery.
Also, the conceived engineering design and subsea architecture can accommodate the potential tieback of additional satellite fields in the area.
For such development, production facilities and engineering choices are highly critical. At the same time they are also strongly impacted by D&C constraints, reservoir input and project objectives. Starting from Angola West Hub experience, this paper addresses the main impacts of such drivers on the engineering of production facilities and subsea fields architecture.
