Deepwater Horizon oil spill 17 of whom were treated for injuries. The Deepwater Horizon sank on the morning of 22 April 2010. The oil leak was discovered on the afternoon of 22 April 2010 when a large oil slick began to spread at the former rig site. The oil flowed for 87 days. BP originally estimated a flow rate of . The Flow Rate Technical Group (FRTG) estimated the initial flow rate was . The total estimated volume of leaked oil approximated with plus or minus 10% uncertainty, including oil that was collected, making it the world's largest accidental spill. BP challenged the higher
Montara oil spill 1 November. The West Triton jackup drilling rig arrived at the Montara Field in an attempt to plug the oil leak on 11 September 2009. Oil and gas producer, Woodside Petroleum Ltd offered to assist PTTEPAA in cleaning up the oil spill with the use of a rig closer to the spill site. However, PTTEPAA rejected the Woodside offer on the basis of "safety reasons". The Woodside rig was a semisubmersible drilling rig and, as it floats on the sea surface, was not deemed as a suitable platform for the relief well. A jackup rig was required because it could