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3.1.2 Gravity Base Structures (GBS). Offshore structures that are placed on

the seafloor and held in place by their weight are called gravity structures. Thus

these structures do not require additional help from piles or anchors. The

construction of a massive GBS utility shaft for Canada’s Hibernia (fig. 3.4) field

development represented a great triumph for Davie. The complex structure

included 9 structural decks, enclosed stairways, mezzanine decks, elevator shafts

and a control room module. Hibernia is the world’s largest oil platform and

consists of a 37,000mt integrated topside facility on a 600,000mt gravity based

structure. Hibernia has been one of the most successful offshore exploration and

production projects in the history of offshore oil & gas.

Figure 3.4 – GBS Hibernia

These structures are quite suited for production and storage of oil. They are

built near-shore location or sheltered water, such as, fjords. Upon construction they

are towed in the upright position to the final destination and submerged in place. It

is often possible to carry the topside deck with the structure. Because of the nature

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