Deepwater: Seafloor systems push the offshore envelope

Subsea oil/water separation has been used for years to lighten high-watercut wellstreams such as at the mature Tordis field in the North Sea, and pumps on the seafloor—both single-phase electrical submersible pumps (ESPs) and multiphase boosting systems—have helped lift hydrocarbons that low pressure or deep water would otherwise put beyond reach. In the future, resources in Arctic waters, for example, will almost exclusively require subsea developments, as floating ice in the region poses a serious hazard to surface facilities. In the meantime, new development projects and established fields are facing novel challenges that require innovative subsea solutions. At Shell’s Parque das Conchas development in Brazil, a pioneering combination of subsea gas/liquid separation and ESP lift is being used to efficiently produce widely varying wellstreams from three separate fields. Meanwhile, Statoil is trying to extend the productive lives of its mature Åsgard and Gullfaks fields offshore Norway through the use of subsea gas compression, making already profitable fields more valuable.