Utilize the input text as a context reference, choose the right relationship between 'Petrobras' and 'gas' from the options.
Options: operator, legal form, product/material produced, developer

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