President Barack Obama cautiously welcomed the news that the leak had been stopped , though stressing , " it is important we do n't get ahead of ourselves " . If the cap holds for the planned 48 hours , its valves will be reopened temporarily in order to allow for seismic tests to ensure that oil is not escaping into the bedrock . At the time of the stoppage , oil had been leaking continuously into the Gulf of Mexico for 85 days , 16 hours and 25 minutes since the '' Deepwater Horizon '' drilling rig exploded on April 20 , 2010
exploded
Deepwater Horizon explosion
Efforts to stem the Deepwater Horizon oil spill