Eni said it signed an agreement with KrisEnergy and Neon Energy for work in the Song Hong and Phu Khanh basins in the Gulf of Tonkin.
The agreement, the Italian energy company said, gives it a larger footprint in the Far East and Pacific region following similar developments in Indonesia and Australia.
Eni, Norwegian energy company Statoil and BP are among the major oil companies moving into the Indonesian energy sector, though its international status was downgraded when it became a net oil importer in 2009 as mature fields decline.
First gas from offshore operations in Vietnam from Anglo-Russian joint venture TNK-BP is expected to move through the 12-inch pipeline during the fourth quarter of 2012. The annual production rate is expected to reach 70 billion cubic feet of natural gas.
Eni said the Song Hong basin holds about 10 percent of Vietnam's hydrocarbon reserves, mostly in the form of natural gas.