Utilize the input text as a context reference, choose the right relationship between Petrobras and gas from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

SAO PAULO (Reuters) - Brazil's state-run oil firm Petrobras (PETR4.SA) said on Wednesday it had signed a contract to sell its 20 percent stake in the Bijupira and Salema oil and gas fields for $25 million (16 million pounds).

Answer: product_or_material_produced