The Yuzhno-Russkoye field in western Siberia produces 25 billion cubic metres per year, OMV said late on Sunday.
"The gas produced there is the key resource for the Nord Stream pipeline transporting Russian gas straight to Germany," OMV said in a statement.
OMV is buying the stake from Uniper, a unit of Germany's EON. Russia's Gazprom is the biggest shareholder in the gas field with 40 percent.
The deal is expected to be finalised by the end of the year, provided it receives the necessary regulatory approvals, OMV said.
OMV and Gazprom are deepening ties as Russia intensifies cooperation with its old partners in western Europe amid international sanctions over Ukraine, Bloomberg reported.