The US-listed drilling company has placed firm orders for two vessels at a cost of $540m each and secured options for three more sisterships.
The first option must be exercised within one year, the second within 18 months, and the final within 24 months.
The two firm units are due to be delivered from Jurong Shipyard in the second quarter of 2017 and the first quarter of 2018, respectively
The combined capital cost for the two drillships is estimated at about $1.24bn
