Gazprom Neft Board As of 31 December 2012, Gazprom Neft and its subsidiaries hold the mineral rights to 74 license areas located in 11 regions of Russia. In Serbia, the Gazprom Neft's subsidiary Naftna Industrija Srbije, holds 69 licenses. Based on an audit of reserves conducted by DeGolyer and MacNaughton and according to the Petroleum Resources Management System standards, the company's proven reserves at the end of 2012 totaled 1.2 billion tonnes of oil equivalent, and its reserve replacement ratio was over 286%. Most of the company's oil production operations in Russia are carried out by three subsidiaries: Gazpromneft-Noyabrskneftegaz, Gazpromneft-Khantos and Gazpromneft-Vostok.
Gazprom in the Nadym-Pur-Taz region (near the Gulf of Ob) in Yamalo-Nenets Autonomous Okrug in Western Siberia. Historically, the three largest fields are Medvezhe, Urengoy and Yamburg. After more than twenty years of production, the fields are now in decline. Production from the fields has decreased by twenty to twenty-five bcm per year. The production at Zaporliarnoe, Gazprom's fourth largest field, increased until 2004, offsetting the decline in the other fields. Since 2004, Gazprom has maintained production by activating new smaller fields and by purchasing production assets from other companies. Gazprom Neft produces crude oil. In 2005, Gazprom purchased 75 percent