The Anglo-Russian joint venture did not disclose either financial details or the buyer for the sale.
Russian news agency Interfax said sources had told it that mid-sized oil producer Russneft was the buyer.
In the deal, Russneft is gaining 100% of Novosibirskneftegaz and 71.09% of Severnoeneftegaz, the latter of which it previously owned before selling to TNK-BP.
The Anglo-Russian venture is shifting focus to producing oil from greenfields in East Siberia.
"This
