Two Chinese companies that entered Brazil’s giant deep-water oilfields two years ago are now looking to increase their presence as state-run Petrobras sells assets to pay down debt, said two people with knowledge of the matter.

China Petroleum & Chemical Corp., or Sinopec, and Cnooc Ltd. are among companies interested in buying stakes in so-called pre-salt offshore exploration blocks, the people said, asking not to be identified because talks are private.

Petroleo Brasileiro SA, as it’s known formally, invited a small group of international companies with offshore experience to bid for stakes in some concessions, including pre-salt blocks, people said last month. The world’s top deep-water producer is looking to raise a total of $15 billion in asset sales this year and next to fund operations and reduce debt that stands at an industry-high $125 billion.

Petrobras didn’t reply to e-mails and phone calls seeking comment. Chief Executive Officer Aldemir Bendine told reporters on Monday that Petrobras wouldn’t comment on negotiations or asset sales before they become official.

While declining to comment specifically on Petrobras’ asset sale, Sinopec Group said in an e-mailed response that it will consider some acquisition opportunities. Beijing-based Cnooc didn’t respond to an e-mailed request for comment, while two calls to its media department went unanswered.

Targeting $5 Billion

Royal Dutch Shell Plc and Statoil ASA are also accessing geologic data on the fields to prepare offers, one of the people said. Petrobras expects bids to be presented as soon as this month, the person said. The company wants to raise at least $5 billion in the offshore auction, the other person said.

Shell is looking for opportunities to grow in Brazil, country manager Andre Araujo told reporters Tuesday. The Hague-based company declined to comment further in an e-mail response. Stavanger, Norway-based Statoil declined to comment.

The fields in which Petrobras is selling stakes, a process known as a farm out, include the Sagitario, Jupiter and Pao de Acucar deep-water discoveries where production hasn’t started, one of the people said. The company has missed asset sale targets in previous business plans.

Petrobras removed the Carcara and Jupiter pre-salt discoveries from its schedule of projects to start producing by 2020, indicating that the fields may be for sale, Bank of America Corp. said in a June 29 research report. Petrobras said by e-mail that it delayed those projects until after 2020.

PetroRio Talks

Asset sales are key for the company to reduce leverage amid low oil prices and after it posted a 21.6-billion-real ($7 billion) loss last year from writedowns related to graft and mismanagement. It would be the first time Petrobras reduces exposure to the pre-salt region it heralded as the world’s next oil frontier nearly a decade ago.

A group made up of Petrobras, Shell, Total SA, Cnooc and Sinopec won a 35-year license to develop the Libra discovery in October 2013. That was the first, and only, pre-salt auction using a production-sharing model that makes Petrobras the operator of all new projects and requires it to own at least 30 percent. Some lawmakers are pushing for those rules to be eased.

In a separate process, Petrobras is preparing to sell its 20 percent stake in the Bijupira and Salema offshore fields to PetroRio SA for about $25 million, said a person with direct knowledge of the deal, asking not to be identified because talks are private. That would be Petrobras’s first divestment of an offshore asset in Brazil under CEO Bendine.