Which Company Faces the Highest Risk of a Slowing Growth Due to the Deep-Water Drilling Ban?

I'll be concise here. The White House's recent 6-month ban on deep water drilling could send ripples throughout the industry, specifically for oil exploration firms that have a large amount of ultra-deep water drilling operations. 

Due to their depth, ultra-deep water drilling exploration is the most risky, and could face some severe and and permanant restrictions down the road. 

So which company is likely to be impacted the most by new regulations in deep and/or ultra-deep water drilling?