During 1973 the general decline in oil production from older onshore fields in Europe continued and was not yet offset by output from the giant oil fields being developed in the North Sea. The North Sea fields were projected for large-scale production to start in 1975. The Amposta Marino oil field off the Spanish coast went on production. European gas production increased, but less than in recent prior years. Large gas fields already had reached their peak rates. In 1973 new giant oil fields producing from Jurassic sandstone reservoirs were discovered in the British sector of the northern North Sea, and major extensions were made to fields found in 1971 and 1972. In the Norwegian area important extensions were made to the Paleocene oil reservoirs of the Ekofisk group of fields, and gas was discovered east of the Frigg field. A major extension to the Kinsale Head gas field off the south coast of Ireland indicated that the field was commercially significant. Oil discoveries were made in France, Germany, and offshore Spain; in addition, new gas fields were found in northwest Germany and both on- and offshore in the Po basin of Italy. Exploration activity, chiefly geophysical surveys, increased in the various basins of the continental shelf off western Europe, from the Barents Sea to Portugal.
In the Soviet Union production of oil was 8,420,000 b/d and of gas 22.8 Bcf/d. Most of the increased oil production was from the West Siberian basin, which became the foremost producing region of the USSR. Production from the giant gas reserves of the northern West Siberian basin reached a significant level for the first time. Exploration in the Caspian Sea was intensified. New oil discoveries were made in the central West Siberian basin, in the Caspian Sea, in the Pechora basin west of the northern Urals, and near the Baltic coast. Gas was found in the Karakum Desert of Middle Asia, on the Siberian platform, and on the shores of the Sea of Azov.