Brazilian state-controlled oil company Petrobras said Friday it would offer voluntary buyouts to some employees in a bid to reduce costs and improve productivity.

The buyouts will be offered to employees 55 years and older in all areas of the company, the company said in a statement, without indicating how many workers would be targeted.

The plan is aimed at lowering costs as Petrobras carries out its 2013-2017 $237 billion investment plan, which is mainly focused on developing a massive, recently discovered oil frontier known as the pre-salt region.

Developing those offshore fields could dramatically increase Brazil's proven-reserve tally and transform the country into a major crude exporter.

But getting to that oil will be costly and technically challenging because the fields are located under water, rocks and a shifting layer of salt at depths of up to 7,000 meters (22,950 feet) below the surface of the Atlantic.

The company said it would strive to "preserve existing knowledge" with the buyout plan, which will affect older, experienced workers.

Petrobras, Brazil's largest company, has roughly 85,000 employees. EFE