Savannah, which has operations in Nigeria, Cameroon and Niger, said the deal would be financed through debt arranged by Standard Bank of South Africa.
The firm agreed to pay $52 million in cash for a stake in the Stubb Creek oil and gas field held by China's Sinopec International Petroleum Exploration and Production Corporation and $9.5 million for the shares held by Jagal Energy.
Savannah's subsidiary Universal Energy Resources Limited, is already the 51% owner and operator of the field.
The deal will secure more gas available for sale to Savannah's Nigerian gas processing and distribution subsidiary, Accugas Limited, which supplies around a fifth of the gas used by Nigeria's power plants.
(Reporting by Isaac Anyaogu, Editing by Louise Heavens)
By Isaac Anyaogu