Shale oil, known also as kerogen oil or oil-shale oil, is an unconventional oil produced from oil shale by pyrolysis, hydrogenation, or thermal dissolution. These processes convert the organic matter within the rock (kerogen) into synthetic oil and gas. The resulting oil can be used immediately as a fuel or upgraded to meet refinery feedstock specifications by adding hydrogen and removing impurities such as sulfur and nitrogen. The refined products can be used for the same purposes as those derived from crude oil. The largest known reserves are in the US. Russian Prime Minister Vladimir Putin has urged his country’s gas industry to rise to the challenge of shale gas as the United States and some European countries forge ahead with developing the controversial energy source. US shale gas production may seriously restructure supply and demand in the global hydrocarbons market, Putin said yesterday in his final address to the Russian Duma before he takes over as president on 7 May.