North Sea oil is a mixture of hydrocarbons, comprising liquid petroleum and natural gas, produced from petroleum reservoirs beneath the North Sea. In the petroleum industry, the term "North Sea" often includes areas such as the Norwegian Sea and the area known as "West of Shetland", "the Atlantic Frontier" or "the Atlantic Margin" that is not geographically part of the North Sea. Brent crude is still used today as a standard benchmark for pricing oil, although the contract now refers to a blend of oils from fields in the northern North Sea. From the 1960s to 2014 it was reported that 42 billion barrels of oil equivalent (BOE) had been extracted from the North Sea since when production began, and there is still a potential of 24 billion BOE left remaining there, which is equivalent to about 35 years worth of production, the North Sea will remain as an important petroleum reservoir for years to come. History 1851–1963 Commercial extraction of oil on the shores of the North Sea dates back to 1851, when James Young retorted oil from torbanite (boghead coal, or oil shale) mined in the Midland Valley of Scotland. Across the sea in Germany, oil was found in the Wietze field near Hanover in 1859, leading to the discovery of seventy more fields, mostly in Lower Cretaceous and Jurassic reservoirs, producing a combined total of around 1340 m³ (8,400 barrels) per day. Gas was found by chance in a water well near Hamburg in 1910, leading to minor gas discoveries in Zechstein dolomites elsewhere in Germany. In England, BP discovered gas in similar reservoirs in the Eskdale anticline in 1938, and in 1939 they found commercial oil in Carboniferous rocks at Eakring in Nottinghamshire. Discoveries elsewhere in the East Midlands lifted production to 400 m³ (2,500 barrels) per day, and a second wave of exploration from 1953 to 1961 found the Gainsborough field and ten smaller fields. The Netherlands' first oil shows were seen in a drilling demonstration at De Mient during the 1938 World Petroleum Congress at The Hague. Subsequent exploration led to the 1943 discovery by Exploratie Nederland, part of the Royal Dutch/Shell company Bataafsche Petroleum Maatschappij, of oil under the Dutch village of Schoonebeek, near the German border. NAM found the Netherlands' first gas in Zechstein carbonates at Coevorden in 1948. 1952 saw the first exploration well in the province of Groningen, Haren-1, which