Deutsche Bank says the US driller may not exercise options for three units at Sembcorp Marine given current industry sentiments.
Transocean signed contracts with the Singapore rig builder in February 2014 for two deepwater units at a cost of $540m each.
The contract included options for three sister vessels the first of which must be exercised by February 2015.
Negative news flow from other offshore drillers has not helped either as they try to combat reduced exploration work by the oil majors.
Noble
