The North Sea oil and gas province is primarily a Mesozoic failed rift basin developed in response to the break-up of the Pangean supercontinent. The associated tectonism controlled deposition of reservoirs, source, and seals and development of structures and thus was the important factor in the generation, migration, and trapping of hydrocarbons.

The tectonic history of the basin can be divided into three major phases: (1) initiation of subsidence as a broad intracontinental downwarping during Permian, (2) tension induced normal faulting and half graben development from Triassic to Early Cretaceous, and (3) a return to broad basinwide subsidence from Late Cretaceous to the present.

The primary reservoirs include Lower Permian eolian sands, Upper Triassic to Middle Jurassic shallow to marginal marine sands, Upper Jurassic and Paleocene deep marine sands, and Danian and Maestrichtian chalks. Primary source rocks are Middle to Upper Jurassic marine shales and Carboniferous coals. The main structures include buried rotated fault blocks and halokinetic features.

Of the approximate 1,400 exploration wells, 490 have been oil and gas discoveries representing a 1:3.5 success rate. Total proved recoverable reserves are over 32 billion bbl oil equivalent with total potential recoverable reserves estimated at 46 to 70 billion bbl oil equivalent. Nine fields contain more than one billion bbl oil equivalent.

More than 53 billion dollars have been invested in the North Sea since 1965. Average cost to find and totally develop fields is approximately 2 billion dollars. At present, at least 100 million bbl recoverable reserves are usually needed for a field to be economic.

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