What is the relationship between 'Petrobras' and 'gas' in the context of the input sentence.
Options: product/material produced, operator, developer, legal form

By the end of 2012, Petrobras said, it would be producing 3.5 million barrels of oil and equivalent natural gas per day (boepd) worldwide, and by 2015 4.6 million boepd, making it one of the world's largest producers.
product/material produced