International oil majors have been trying to sell stakes in onshore oilfields in Nigeria for years as they pivot their investments to assets offshore the West African nation and to other regions.

Shell, Total and Eni each sold stakes in the OML 17 field, which has production capacity of 27,000 barrels of oil equivalent per day and estimated reserves of 1.2 billion barrels of oil equivalent, Heirs said.

TNOG Oil and Gas Limited, which Heirs owns alongside Transnational Corporation of Nigeria Plc, officially took the stake.

"The acquisition of such a high-quality asset, with significant potential for further growth, is a strong statement of our confidence in Nigeria," Tony Elumelu, the chairman of Heirs Holdings, Transcorp and United Bank for Africa Plc, said in a statement.

In a separate statement, Shell Production and Development Company of Nigeria (SPDC) announced a $533 million sale of its 30% stake in the OML and said it had received all necessary approvals from Nigerian authorities.

Standard Chartered Plc, United Capital Plc and a syndicate of lending institutions advised on the deal, which involves Schlumberger as a technical partner and Shell's trading arm as an oil offtaker.

(Reporting by Libby George; Editing by Nick Macfie and Paul Simao)

By Libby George