Fact box – The North Sea is unique

The Norwegian sector of the North Sea is the most explored area of the NCS, and also where the largest quantities of oil and gas have been proven and produced.

Norway’s oil adventure began at its southern end, with the discovery of Ekofisk in 1969. Ranked then as the world’s largest offshore field, it has been on stream for more than five decades and current plans expect production to continue for almost another 30 years.

Large quantities of oil and gas were subsequently proven in the northern North Sea with the Statfjord, Gullfaks, Snorre, Oseberg and Troll fields. Over 400 million scm of oil were proven in Johan Sverdrup in 2010. That made this the fifth largest oil discovery ever on the NCS. These giant discoveries demonstrate that the North Sea is one of the world’s best petroleum basins.

The reasons why this area contains so much petroleum are complex, and depend on several geological factors which arose in the Jurassic (145-201 million years ago). These processes created a very favourable setting for all the key conditions in forming oil and gas fields, namely source, reservoir and cap rocks.

These included the deposition of Draupne shale, known as one of the world’s best source rocks for oil and gas.

Conditions for forming oil and gas fields are also present in the Norwegian and Barents Seas, but the geological processes have been different from those in the North Sea and not as favourable.

Although substantial undiscovered resources remain on the NCS, 76 per cent are estimated to have already been proven. Resource growth for each NCS area, as illustrated in Figure 2.7, demonstrates the uniqueness of the North Sea. Even if expected undiscovered resources are proven in the Norwegian and Barents Sea, the quantities will nevertheless be far lower than the volume proven in the North Sea.