What do we know about the Deepwater Horizon disaster? The
Deepwater Horizon rig disaster caused the deaths of 11 crew and
a massive oil spill in the Gulf of Mexico. Since the 20 April
catastrophe there has been much discussion in US Congressional
hearings and the media about the sequence of events that led up
to it. Here is a summary of what we know so far about the BP oil
spill, and the primary questions that are still being
investigated. The Deepwater Horizon rig was drilling an oil well
in the Macondo prospect that was intended to be plugged with
cement and then completed later to become a production well. The
top of the well was about 5,000ft (1,524m) beneath the surface
of the Gulf of Mexico. The Deepwater Horizon was owned and
mostly staffed by employees of exploration firm Transocean,
under contract to BP. The nature of the well - BOP: Blowout
preventer - stack of valves designed to stop blowouts - Blind
ram shear: Last line of defence in BOP - cuts pipe -
Centraliser: Device to keep pipe or casing in