A 'normally unmanned installation' is a type of offshore facility that is designed to be operated remotely without the constant presence of personnel. They are characterized by their small size, often consisting of just a
well bay with a
helipad on top. They are often a compromise of providing the convenience of surface
wellheads, which are easier to build and maintain, while avoiding the high operating costs of a full
production platform.
They are generally only used in shallower water, where constructing many small NUIs is a relatively easy and cheap option as compared to the cost of using subsea wells. This can be seen in the Southern
North Sea where large numbers of wells are on smaller NUIs, compared with the more northern areas of the continental shelf where fewer larger platforms and subsea sites are the norm.
NUIs are commonly serviced from a nearby larger platform, eg,
Mungo serviced from
Marnock. These installations will include an emergency shelter with essential food and water in order to provide a safe refuge in the event that weather or other considerations prevent a visiting crew from returning to base. Regular visits may be made for routine maintenance and for smaller
well work such as
wireline operations. Anything larger requires a
drilling rig to be brought in, but this is still an advantage over subsea wells, which require a
drilling rig or light intervention vessel for any
well intervention.
See also
★
Oil platform