The oil spill in the Gulf of Mexico has triggered fresh questioning inside the oil industry about the safety of deep offshore drilling, one of Britain's top inspectors has told the BBC.
The blowout on BP's Macondo well 5,000ft deep has forced oil firms to review their technology and systems, according to Donald Dobson of the Health and Safety Executive.
In an interview in Aberdeen, one of the world's leading support centres for offshore drilling, Mr Dobson told me that regulators and industry are asking a series of questions.
They are asking whether they can drill safely, whether their systems are adequate, and whether they have properly identified the risks, assessed them correctly and are taking the correct precautions to avoid them in future.
"What's happening now is that the industry is looking at how it does things, checking that they are following the correct procedures, and that they aren't inadvertently straying from good practices, making sure all their equipment is functioning as it should," says Mr Dobson.
"It's making people go back and double-check things that they've taken for granted in the past."
His comments come amid mounting concern about the risks of deep wells offshore.
The US administration has imposed a six-month moratorium on deep drilling while the BP disaster is investigated.
Mr Dobson, who leads a team of inspectors monitoring the safety of oil and gas wells in the UK, identifies several factors that add to the risks of deep-sea operations:
- The sheer distance from rig to seabed means that the usual hydraulic systems - for example those used to shut off a well during an emergency - cannot be relied on to respond rapidly enough.
- Waters deeper than 400m are beyond the reach of divers and although remotely operated vehicles are increasingly sophisticated, there are limits to their effectiveness. An ROV "can push buttons and turn handles but that's about all" it can do.
- Temperatures are so low at depth that if there's a leak in the riser pipe - bringing oil to the surface - the icy waters could freeze the methane that flows with the oil and block the flow.
This comes as the oil industry is pushing into deeper waters in its quest for new supplies.
The example of the Gulf of Mexico is most striking.
The US Minerals Management Service reports that in 1997 there were 17 producing deepwater projects in the region - compared with 141 in 2008.
Globally, deepwater projects are now found off Brazil, Angola and Asia. According to the ODS-PetroData, there are 160 deep oil fields in production with another 88 being planned.
Some estimates say that about half of all offshore oil is now coming from deep-sea sources.
This is only possible with technological advances unimaginable a decade or two ago - sophisticated robotics, for example.
And demand is projected to grow. Discoveries of new oil reserves on land are infrequent - or relatively inaccessible - and those in shallow seas tend to be small.
But, as events in the Gulf of Mexico show, pioneering operations in the depths of the ocean carry risks.
And the speed with which the leak is stemmed, and the spill contained, may determine how rapidly the industry's advance into the deep continues.