Gulf oil spill: BP press conference live

5.45pm:

BP revealed yesterday that plans to stop oil leaking into the Gulf of Mexico following the Deepwater Horizon explosion had suffered a setback when a build up of crystallized gas blocked pipes in one of its giant sunken towers.

The oil company's long term plan is to drill a relief well from a second oil rig in the Gulf, allowing it to continue to extract the oil. In the meantime BP is attempting to reduce the effect of the leak using chemical dispersants and containment booms, and will try again to manouevre the cofferdam into place.

However it has also been suggested engineers are investigating the possibility of plugging the leak using a "junk shot" – essentially firing debris into the well to block it.

Follow live updates from BP here, and email adam.gabbatt@guardian.co.uk or tweet @adamgabbatt with your thoughts.

6.00pm:
We're due to begin any minute. I'm just being bombarded with classical music at the moment.

6.03pm:

Tony Hayward (BP chief exec) kicking off proceedings.

6.05pm:

Hayward says they fight the leak on three fronts - beneath the surface, on the surface, and on the shore.

In the "subsea" – it is the first time the industry has had to deal with anything at this depth. A lot of "real time learning going on".

Hayward says the dome wasn't as successful as they'd hoped. There is a lot more gas emerging than they had thought.

In the meantime they are moving to position a smaller dome.

6.06pm:

They refer to the smaller dome as a "top hat". It's about the size of a barrel - a lot, lot smaller than the 12m high cofferdam they had started using.

It will be a lot less effective in capturing the oil, but could be operating within 72 hours.

6.07pm:

The other measure on the sea bed is to tap into the riser further along the sea bed, and "tap into" the riser directly, without having to mess around with sea water contamination.

The riser is essentially the pipe that would have pumped the oil to the surface before the explosion.

6.09pm:

BP have "an armada of ships" skimming oil. They've skimmed over 100,000 barrels of oily water, as well as spraying dispersant.

They now have a million feet of boom deployed, with a further 2.5m in transit. They have thousands of volunteers signed up, and thousands of vessels have applied to participate in the clean up, although at the moment the oil is "not getting anywhere near the shore," Hayward says.

6.12pm:

Hayward taking questions.

"Could you say why an effort like this wasn't anticipated to a greater extent and why you're having to make it up as you go?" asks a journo.

The investigation of this incident will through up things we should have been doing differently, Hayward says. Particularly on the failure of the blow out preventer and the inadecuacy of the industry to act at such depths.

The industry has not hitherto had an issue of this sort to contend with, he says.

Until you come to a specific problem it is difficult to know what you may need to solve it. A lot of learning is going on.

6.16pm:

What are the risks of the junk shot? Could it make matters worse?

The risks of that are very very very very low, Hayward says. BP will be trying to make sure this intervention has upsides and no downsides.

There have been fears that the junk shot could damage partially working valves which are preventing the leak from being as bad as it could be.

Why didn't the dome work?

In the design criteria of the larger dome, we can't pump enough water down over it to stop it freezing, Hayward says. The smaller dome should not be as susceptible to the freezing which prevented the first from working.

6.19pm:

There'll probably be some generic lessons to be learnt, Hayward says. But he won't speculate.

What will the leak mean for BP and the industry?

It's a serious situation for BP, Hayward says. We will resolve it, its just a question of how long it will take.

I suspect there will be specific findings regarding the ability to intervene 5,000ft underwater, he reckons. There should be lessons for the industry.

6.22pm:

Is the junk shot going directly into the well bore?

No. It will go down "choke and kill lines", into the blowout preventer. Then it will seal the blow out preventer. They would be pumping material into the internals of the blowout preventer, Hayward says.

I think the junk shot will go into the blowout preventer.

6.25pm:

Why was BP so unprepared? Were there flaws in the level of preparedness?

Hayward says the company is implementing its spill response plan rigirously. It has been very effective in stopping oil getting to the shore. It is the largest spill response effort mounted in the history of the industry.

He says the issue of preparedness is around the blowout preventer. The industry will learn from this and make more changes.

6.27pm:

Tell us about the drilling of the relief well, and what you have in place if that doesn't work? What are the risks it doesn't work?

We're drilling two relief wells, says H, to give ourselves "belt and braces". This should guarantee success.

No plan B?

The relief wells will be successful says a confident Hayward.

6.28pm:

How do you know you've been successful if you don't know how quickly the oil is coming out, asks a hack?

By the fact we have contained the oil within the immediate vicinity of the well, says H.

6.28pm:

Hayward's off. Kent Wells, senior vice president in BP's exploration and production business is taking over.

6.31pm:

Wells is elaborating on the technical aspects. Specifically "sub sea".

This is an unprecedented challenge, he says. BP has assembled a small army. They have people from just about every oil and gas company, from the government, from everywhere.

BP wants multiple options at combatting the spill. They're "designing every option to be successful, and planning for it to fail". Good line.

6.34pm:

He's going to talk about the top hat, then the junk shot.

BP felt the big cofferdam (the 90 tonnes one) was the best option. But they were aware it may not work. It had a 12 inch opening, and they were going to pump warm water down the pipe to keep it warm and prevent the slush effect that actually ioccurrec, stopping them from pumping off water.

It didn't work though.

Now they've gone from "one extreme to the other". The "top hat" dome is 5ft tall, 4ft wide. Warm sea water will be pumped down. As they lower the dome it will already be operational - hooked up to a ship on the surface. It will be more difficult to place but they will succeed.

It should be in place by the end of the week.

6.37pm:

BP is also trying to shut off the flow. Control pads connected the blowout preventer don't work because they were attached to the rig, which sank.

The junk shot will bung up the blowout preventer. They want a mix of different size of materials that will go in and hold - such as golf balls. BP has been experimenting with different "recipes" of junk

6.39pm:

If one recipe doesn't work they'll try something else. They will follow it with cement, and permanently abandon the well. It will take up to two weeks to work.

Shutting of the well (in this fashion or any other) is BP's number one priority.

6.42pm:

More on the junk shot.

Choke and kill lines give an access through valves into the well. The junk shot would go down those lines and clog up blow out preventers. It has been used elsewhere successfully, but not at 5,000ft - nothing has, Wells says.

Could the junk shot make matters worse?

Every time they've done something they've considered if it could make matters worse, W says. They "really believe this is going to pull it off".

6.44pm:

BP have put out a phone number to members of the public saying they can contact the company with suggested solutions, a hack says. Have any of the solutions so far come from the public?

Wells says he couldn't know where all the ideas come from. All are processed, he says.

6.44pm:

How do you get the shot in when stuff is coming out of the hole?

It is separated into 10 different segements. Then BP will turn the valves and shoot it in. They'll be able to make repeated shots.

BP will use "whatever pressure it takes to pump into the well". But it will take a lot of pressure, Wells says.

6.47pm:

They definitely will be using golf balls, W confirms. Pieces of tyre too.

6.49pm:

The relief wells take 90 days to get into business, and they started work on the first one a week ago. Work on the second will start in a week.

6.51pm:

Questions coming from the phones. Fingers crossed.

Ah. It's not me. But nonetheless - what percentage of the oil will be contained by the top hat? Why wasn't the top hat tried first? Was it because they then have to abandon the well?

Keeping the well open was the last thing on their mind, Wells says.

Immediately they were trying to shut down the BOP (blow out preventer).

6.53pm:

Have you considered collapsing the formation with military action?

Wells says again that they are not worried about losing the well. He is unaware of any technique of bombing the well. It's a long way down.

My request for a question is going unanswered.

6.54pm:

What is the 90 day estimate based on?

That is how long it will take to intercept the well. There could be complications but 90 days is the plan.

The second relief well is being drilled incase they run into problems with the first one.

6.56pm:

How sure are you that only 5,000 barrels a day are coming out?

We don't know what it is, no way to measure it, says Wells. No accurate way to put a measure on that.

6.58pm:

One of the ideas behind big containment chambers was that it would embed itself in the surface, asks an American journalist.

How can you be sure a small one will not be moved around by the flow?

The big dome was so heavy because it was so large, says W, not really answering the question. The smaller dome will be held in place by the drill pipe and riser, so that is why it should work.

7.00pm:

Wells says BP would like to reassure everyone there is a dedicated team working on this, and they will get it under control.

Eventually they will bring the BOP up to see what went wrong with it, Wells says. And with that, he is off.

7.10pm:

Email from Eric Rubenstein:

Adam,

You wrote in your blog that the question was asked as to the percentage of oil that will be contained by the top hat.... what was the answer to that question? or did the question go unanswered?

Good spot, unfortunately it wasn't properly answered. Wells said he would not speculate as to how much it might contain. (Which is a bit odd seeing as figures were around about how much oil the large dome was expected to recover. Maybe BP have learnt their lesson.

7.14pm:

That's that.

Wells confirmed that the contents of the "junk shot" really will be as primitive as they sounded. Golf balls and bits of old tyre.

He was very defensive about questions regarding whether BP did not want to use this measure at first as it would mean losing the well, stressing two or three times that saving the well was never on the company's mind.

Both Wells and Hayward didn't provide information on how much oil is spilling out, as they haven't from the start, but Hayward in particular went to great lengths to stress that the clean up operation was "2 or 3 times larger" than any that has been staged before.

There was a lot of talk of "learning as we go along" and how this spill was unprecedented.

While it is true that there is no precedent for a spill at this depth – the technology is relatively new – a lot of journalists pointed out that should not mean a spill should have have been unexpected, which is why we saw questions on whether BP should have been better prepared.

All Hayward would say on the issue was that the industry will be able to learn from the investigation into the incident. He said there will probably be specific findings as to how to deal with problems 5,000ft underwater. Will that satisfy the critics? Possibly not.