The group of pipelines, considerably smaller than the TAG unit sold by Petrobras, as the company is known, could be valued at more than $3 billion altogether, one of the sources said.

Petrobras has hired the investment banking unit of Credit Suisse AG to sell the pipelines that link oil fields in the so-called pre-salt area in the Santos basin to onshore infrastructure, said the sources, who asked to remain anonymous as the discussions were not yet made public.

Petrobras and Credit Suisse declined to comment.

Petrobras had initially planned to sell only a minority stake in the units, but after getting a better-than-expected price for the TAG unit, the company may sell control of the pipelines, two of the sources said.

A controlling stake would lure more investors than a minority one, one of the sources said. Some of the investors that participated in the TAG deal were interested in the other pipelines, which similarly offer table cash flows.

A final decision will be made once Petrobras' new Chief Financial Officer Andrea Marques de Almeida, who was appointed last month, starts in her new role, one of the sources said.

The three units, known as Rota 1, Rota 2 and Rota 3, comprise roughly 1,000 kilometers (621.37 miles) of pipelines stretching from the Santos basin to the coast.

Two of those units already transport natural gas generated in sub-salt fields in the Santos basin to onshore facilities in the coast of Rio de Janeiro and Sao Paulo, and the third one is still under construction.

The process of selling the additional pipelines will probably not start before the second half of the year, one of the sources said. That's because Petrobras needs to get the approval of its oil exploration partners in the pre-salt oil fields for the sales since they own stakes in the natural gas production in the fields.

Those partners include France's Total SA, Royal Dutch Shell Plc and China's CNPC.