The deal, which already secured US Federal Trade Commission (FTC) approval, has now received preliminary approvals from the competition authority without restrictions.
An unnamed Shell spokesperson was quoted by Reuters as saying that the CADE, however, has given a 15 day appeal.
The clearance would be considered final by CADE only if no appeals were lodged or referrals made during the period.
Expected to be completed by early 2016, the transaction is due to secure pre-conditional approvals from the European Union, Australia and China.
The Shell and BG merger decision, which was announced in April 2015, comes amid declining global oil prices.
Both the firms have stakes in Brazil’s oil producing fields. BG has 25% stake of the Lula field while Shell holds 20% interest in the Libra project.
According to the news agency, state-owned oil giant Petroleo Brasileiro also intends to divest its assets in order to reduce its debts and increase investment to enhance output.
Petroleo Brasileiro is the operating partner for BG and Shell in major Brazilian offshore projects.
