It seems that not a lot went right on the Macondo welll on April 20. If you need a step-by-step description of events that led to the accident, here is BP’s more detailed account, helpfully attributing blame at each step (the emphasis is ours).
- The cement and shoe track barriers – and in particular the cement slurry that was used – at the bottom of the Macondo well failed to contain hydrocarbons within the reservoir, as they were designed to do, and allowed gas and liquids to flow up the production casing;
- The results of the negative pressure test were incorrectly accepted by BP and Transocean, although well integrity had not been established;
- Over a 40-minute period, the Transocean rig crew failed to recognise and act on the influx of hydrocarbons into the well until the hydrocarbons were in the riser and rapidly flowing to the surface;
- After the well-flow reached the rig it was routed to a mud-gas separator, causing gas to be vented directly on to the rig rather than being diverted overboard;
- The flow of gas into the engine rooms through the ventilation system created a potential for ignition which the rig’s fire and gas system did not prevent;
- Even after explosion and fire had disabled its crew-operated controls, the rig’s blow-out preventer on the sea-bed should have activated automatically to seal the well. But it failed to operate, probably because critical components were not working.
The report also goes on to say that it is “unlikely” that the design of the well itself was at fault, because the investigation found that “the hydrocarbons flowed up the production casing through the bottom of the well”. This is key as BP was responsible for the design, which was signed off by Anadarko and Mitsui, its partners on the project.
As Sylvia Pfeifer, FT’s energy correspondent, points out avoiding a finding of gross negligence from official inquiries into the accident is an important objective for BP, as that would potentially limit its penalties under the US Clean Water Act to about $5bn rather than a possible $21bn.
BP’s investigation team includes a series of recommendations based on their key findings. The report notes that ”others in the industry may benefit from consideration of these recommendations as well”.
Investors seem happy enough with the report: the company’s stock is up about 2 per cent in London, against a flat FTSE 100 index.