High Quality Content by WIKIPEDIA articles! North Sea oil is a mixture of hydrocarbons, comprising liquid oil and natural gas, produced from oil reservoirs beneath the North Sea. In the oil industry, the term "North Sea" often includes areas such as the Norwegian Sea and the UK "Atlantic Margin" (west of Shetland) that are not, strictly speaking, 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. 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.