Samotlor Field is the largest oil field of Russia and the sixth largest in the world. The field was discovered in 1965. Development started in 1967 and first oil was produced in 1969. The field is located at Lake Samotlor in Nizhnevartovsk district, Khanty–Mansi Autonomous Okrug, Tyumen Oblast. It covers 1,752 square kilometres (676 sq mi) Discovery of this field had changed Nizhnevartovsk from a small nearby village into a busy oil city as Samotlor used to be the most important oil production base of the Soviet Union.
The Urengoy gas field in the northern West Siberia Basin is the world’s second largest natural gas field after South Pars / North Dome Gas-Condensate field. The gas field has over ten trillion cubic meters (1013 m³) in total deposits. It lies in Yamalo-Nenets Autonomous Okrug in Tyumen Oblast of Russia, just south of the Arctic circle and named after the settlement of Urengoy. Urengoy gas field was discovered in June 1966.The first drilling hole hit gas on 6 July 1966 and the field started production in 1978. On 25 February 1981, Urengoy extracted its first one hundred billion cubic meters (1011 m³) of natural gas. From January 1984, Urengoy gas started to be exported to Western Europe through the Urengoy–Pomary–Uzhgorod pipeline.