The Hanoi-based group said in a statement it aimed to add between 30 million to 40 million tonnes of oil equivalent to its total oil reserves annually, to "guarantee national energy security".
This year, the group said it aimed to purchase two major oil fields in Kazakhstan and Azerbaijan.
Petrovietnam's exploration arm PVEP said it had acquired assets, most of which were under exploration, in Algeria, Malaysia, Indonesia, Iraq, Mongolia, Venezuela and Madagascar.
Vietnam now ranks as Southeast Asia's third-largest crude oil producer after Indonesia and Malaysia, with 2008 oil production forecast at about 320,000 bpd, all for export as it lacks refineries.
The country's first oil refinery, the 140,000-bpd Dung Quat plant, is scheduled to go onstream in February 2009.
(Reporting by Nguyen Nhat Lam; Editing by Valerie Lee)