Formation and Distribution of Giant Oil and Gas Fields in North Sea Basin

North Sea Basin is a typical Mesozoic rift basin, of which the formation and distribution of oil and gas has obvious characteristics. To understand the oil and gas formation and distribution could guide the exploration of other rift basins. Based on the relevant data provided by CC and IHS, combined with the generation, reservoir, cap rock and trap features research, this paper analyzes the 57 giant oil and gas fields found in the North Sea Basin and adjacent areas, and concludes that the gas source rock of southern North Sea Basin is Westphalian coal of Upper Carboniferous, the main oil source rock of northern North Sea Basin is the shales of Kimmeridge Clay (Britain), Mandal, Draupne (Norway) and Farsund (Denmark) Formations from Upper Jurassic to Lower Cretaceous; the main reservoir of southern North Sea Basin is Rotliegendes sandstones, the Middle Jurassic Brent Group sandstones in Viking Graben and Upper Cretaceous chalk in Central Graben to the north; the regional cap rock of southern North Sea Basin is halite, and mud limestone to the north. It is also found that the critical factors that control the formation and distribution of giant oil and gas fields are: the distribution and maturity of effective source rock, the development of good reservoir rock and its distribution, the development of halite tectonic, fault block anticline and tilted fault block trap induced by halite and faulting movement during syn-rift period, the effective sealing by regional halite and mud limestone. Owing to these beneficial factors, the North Sea Basin is generally characterized by gas generation in the south and mainly oil generation in the north. Locally, because of the distribution of Brent group, and structural movement of regional halite in Central Graben, most giant oil and gas fields concentrate in northwestern Viking Graben and Norway area in middle of Central Graben.