Consultant will determine financial feasibility of investment program to transport crude through the Norperuano pipeline.
New players will come into Brazil's downstream business and create competition and possibly also changes in the country's commercial policies, according to a Petrobras executive.
The aim is to boost production, bringing in new short-term investments.
Proven plus probable (2P) reserves totaled 2.9Mb at the end of 2017, down from 4.6Mb a year earlier, according to a company statement on Wednesday.
Colombians will choose a successor to President Juan Manuel Santos on May 27, with a runoff vote scheduled for June 17.