In 1917 the Bolshevik coup was strongly supported by the oil workers and a Soviet regime was initiated in Baku in November. The new Soviet government attempted to increase oil production, but in spite of all efforts, output continued to fall. The Baku-dominated phase of the Soviet oil industry came to an end in the mid-1950s with the development of the Volga-Urals intra-continental composite basin located between the Volga River and the Ural Mountains. In 1981 total Soviet petroleum liquids production was a reported 4.446 billion barrels. The Soviet Union lacks advanced petroleum exploration and production technology. The Soviet Union contains the largest natural gas reserve in the world, about 1,160 trillion cubic feet or about 6 times the reserve of the United States. Total Soviet gas production in 1981 was officially estimated at 16.38 trillion cubic feet, an increase of 7 percent over 1980.