Depth of Gulf oil spill challenges containment efforts | Science| In-depth reporting on science and technology | DW | 06.05.2010
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Science

Depth of Gulf oil spill challenges containment efforts

From relief wells to a giant funnel, clean-up continues at the oil spill in the Gulf of Mexico. Dr. Simon Boxall of the UK's National Oceanography Centre told Deutsche Welle about the options - and obstacles - involved.

A worker oversees an oil boom collecting oil from a leaking pipeline

The explosion of an oil rig in the Gulf of Mexico triggered a severe leak

Deutsche Welle: What are the mechanics of the leak at BP's underwater well - and why is it expanding so quickly?

Dr. Simon Boxall: Basically, it's an exploratory well, and what they've been doing is drilling into the oil seams to explore and understand what oil is down there. Now, what they've actually done is opened up a hole in the earth through which oil is leaking, and the estimated rate is about 700 tons per day, or 5,000 barrels. Now this isn't a major oil spill at this stage. Putting it into perspective, this is 1 to 2 percent of the Exxon Valdez spill per day. The problem, of course, is it's an ongoing spill, and if it's left unchecked, it will become a major disaster. So it's important it's plugged as quickly as possible.

BP has already started drilling a relief well to contain the leak - but that's a process that takes months. How many relief wells would be necessary for a spill of this size, and how do they work?

Basically, a relief well is like having a water pipe, and the water pipe springs a leak - and then what you're doing is effectively drilling a hole in the water pipe further down, tapping the water off. So you then stop the flow of water to the broken pipe and you can then fix the pipe. In this case, I wouldn't know how many holes they need to drill, but it does take time to locate the right place and then to get the drilling equipment into place. It's not a quick process. So what they need to do and what they're doing at the moment is finding ways of tapping the leak or containing the leak while they get on with the longer-term fix. So drilling relief wells is sort of the long-term fix-it. In the short-term, they need a Band-Aid or bandage over the whole thing to stem the flow.

Workers prepare oil booms to contain the spill

Oil booms help protect coastlines, but work best in confined areas

And what are these Band-Aid solutions? Which short-term, targeted solutions could work?

If one were working on land or in very shallow water - for example, in the North Sea - then these are very simple tasks. But because we're working 1500 meters down, the pressures at these depths are phenomenal - in excess of 1500 tons per square meter. And the other problem, of course, is that with this remoteness, we can't put people at those depths; we're reliant on robots. Visibility is poor, and we're working very remotely from ships on the surface. So it's a very difficult place to get to - and this is the big problem.

So they're building a big funnel, which they will place over the hole. It's a low-tech approach, but low-tech works best when you're working in such extreme environments. They're lowering a low-tech funnel over the hole, and it's attached to the pipe, and that will collect the rising oil, which can then be safely put into ships and taken away from the area. So the solution is a sensible solution, because it's simple and it should work. But we'll find out, hopefully in the next five or six days.

A graphic depicting the plans for a containment chamber and funnel

The depth of the leaking pipeline has hampered easy access to the site

But as you'd mentioned, the leak in the Gulf occurred under about 1525 meters of water. Is this kind of device likely to function at these depths?


There's nothing not to function - it's simple. It's a mechanical device, it's literally a shaped funnel with a box put over the whole thing. There's nothing to go wrong if they can locate it over the spill, and that's the big problem: getting the location right. They need to use robots to do that, and these are tethered to the surface. And the big problem, of course, is we would (normally) only operate with one robot tethered to the side of a ship at the same time, whereas we have several robots operating to try to locate the funnel over the hole, and there are technical difficulties in terms of all the strings of the robots tangling up with each other. So it is going to be a difficult task - it's not simple. And the simpler they can make the fix, the better. This is what we call a "belt and braces" approach in England: using old-fashioned technology and hoping it works.

What about other operations, such as skimming and controlled burns?

What they're tackling now is how to stop the oil from getting into the environment, which is the best option. In terms of dealing with the oil that's in the environment, the best option is always to leave it alone, because if it's not doing any harm - in other words, if it's not going ashore - in the open ocean, the oil disperses very quickly, it biodegrades through bacterial decay. And particularly in the Gulf of Mexico, where the waters are warm, it would actually disperse into the environment.

Remember that oil is a natural product: It's something that came out of the ground; it was laid there by the earth. And oil has been seeping into the sea for millions of years - well before we came along - naturally. So the best option is always to try and leave it alone if you can. The second-best option is to pick it up using skimmers, and using pumps to get it off the surface of the water is a good option because it takes it out of the environment quickly and then we can deal with it easily. The problem with that is the oil needs to be fairly young. Once it starts to mix with water, it turns into what we call an "emulsion," or a mousse. And when that happens, it becomes more difficult to skim it or pick it up from the sea surface.

Workers load oil booms onto a boat to assist in the containment of oil

Tackling the spill involves both containment and clean-up efforts

We can protect coastal areas with booms, but the problem is that because this oil is filtering up through 1.5 kilometers of sea water, by the time it reaches the surface, it's not a nice, neat patch; it's spread over a large area. So booming becomes difficult because of the large area that's going to be affected. Now although this isn't a big spill, because it's a continuous spill, then it's a bit like a kind of garden spray rather than a garden hose - you're spreading it over a much larger area, albeit thinner. Booming larger areas becomes difficult because we just run out of booms. The other problem with booms is, of course, if you have bad weather, the booms are totally ineffective.

Burning the oil is never a good option, except in very extreme cases. The problem with burning is that you're actually transferring toxins into the environment … and you actually build up a residue which can be as harmful as the oil itself - you don't totally burn the oil. Bear in mind also that because the oil emulsifies as it moves to the surface, it doesn't burn that easily anyway.

The third option, of course, is dispersants - chemical dispersants - and what they do is move the oil through the water column, so it dilutes the oil … Now the only downside of dispersants is that in past years, dispersants were more toxic materials - you were adding to the problem rather than solving the problem. Modern-day dispersants tend - and I use the word "tend" - to be less harmful, so they are an option if you're protecting an area that's going to be hit by an oil slick. But generally speaking, they're not a favored option if the oil is out at sea. If it's out at sea, the best thing to do with the oil is to let it disperse naturally and let it break down in the environment …

Are there technologies that oil companies can utilize to prevent spills in the future?

The bottom line is, this accident was waiting to happen. Everyone knew that sooner or later, there would be a deep-sea blow-out or spill. We're working in an area that is very inaccessible. It's probably as easy to work on the moon as it is to work at these depths. And the problem is, once an accident happens, there is no protocol, there is no experience of how to deal with this sort of spill … It could have been any of the big oil companies at any stage over the next three or four years, and it just happens to have been BP that has been unlucky. As long as we want oil, we will need to drill in these inaccessible places.

Small remnants of weathered oil in the Gulf of Mexico

Once oil mixes with water, it emulsifies and becomes tougher to remove

Since the spill in the Gulf, California Governor Arnold Schwarzenegger has withdrawn his support for drilling off California's coast. How likely would you say it is that a disaster like this could happen again in the future?

It will happen - it's not if, it's when. One of the concerns we have now is where they're looking at big drilling programs in the Arctic. At the moment, there are plans around the world to drill in the Arctic in the next few years. There are huge reserves of oil under the Arctic Sea, and we're going to be meeting the same problems in the Arctic as we are in the Gulf of Mexico. So we need to ask ourselves: Are we prepared to put up with or to accept spills and damage to the environment for oil? It's not just California - it's also the Arctic.

Dr. Simon Boxall is an oceanographer at the National Oceanography Centre in Southampton, Britain, with expertise in oil spill clean-up.

Interview: Amanda Price
Editor: Nathan Witkop

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