French oil group Total has announced the sale of its 20 per cent stake in a Nigerian offshore bloc to China's Sinopec for $US2.5 billion ($A2.4 billion).

The OML 138 bloc, which includes the Usan oil well already in production since February, is co-owned by US groups Chevron and ExxonMobil and Canadian company Nexen.

In September, Total announced a asset sale program worth $US15 to $US20 billion to be carried out between 2012 and 2014. With the Nigerian divestment, Total has so far raised $US7.5 billion.

"The transaction is aligned with Total's active portfolio management," said Yves-Louis Darricarrere, president upstream at Total in a statement.

"Usan accounts for less than 10 per cent of the group's equity production in Nigeria. This sale of an asset operated from a minority position will allow us to focus our resources on the material growth opportunities in Total's portfolio," he said.