Brazilian state-run oil company Petróleo Brasileiro SA (Petrobras) and China National Petroleum Corp. (CNPC) have agreed to look into whether the unfinished Comperj oil refinery in Rio de Janeiro would be economically viable if it were completed, Reuters quotes Petrobras as saying.

The news agency says that if the study found that the refinery would be viable, Petrobras and CNPC will form a joint venture to complete and run the refinery.

Petrobras would own 80 percent of the venture and CNPC the rest.

The report says the agreement also gives CNPC 20 percent of the oil concessions of the Marlim cluster off the Brazilian coast.

The agreement was foreshadowed by a letter of intent signed by representatives of Petrobras and CNPC in July, Reuters says.