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Reading the latest bbc article on the Elgin platform leak - apparently the flare is still merrily burning away 90m above between 2 and 23 tonnes of explosive gas.
Happily UK government energy minister Charles Hendry is confident that the two won't meet. I mean, it's not as if it's occassionally windy out in the North Sea.
Wonder if anyone's sent him the GasSafe leaflet yet.
I overheard an oil industry worker on the train yesterday. He was reassuring his mum on the phone that he was not in that field, nowhere near, and not to worry. Apparently, according to him all the workers were evacuated from the rig, took about an hour to lift everyone off by helicopter.
The lightest flammable component of the gas condensate will probably be methane - does it / can it / will it rise through air?
It can, I'm pretty sure its lighter than air, but it also is pretty thin and disperses very quickly. You'd need enough concentration to ignite and 90m is a fair way to disperse.
Almost certainly it would. At STP, the density of methane is about half that of air.
But since what's leaking is gas condensate, which is a heavier mix of hydrocarbons and is liquid at STP, unless there's a massive updraught that disturbs the overlying vapour it's probably not an immediate explosion risk, unless something else happens to spark it.
Interesting to see Jake Molloy commenting. He was doing the same job during Piper Alpha's time.
Frankly I'm still amazed that rigs still flare excess gas. Wake up world, this stuff doesn't grow on trees.
I believe they're only allowed to flare for safety reasons in UK territory. Most companies comply with this given the value of gas it benefits them too.
At a refinery most only send gases to the flare when a pressure release is tripped and it risks explosion, though this is as much to do with the refinery using these gases as fuels as environmental issues.
Hadn't twigged that condensate implied liquid, doh! Still if there's enough gas emerging to make the water surface appear 'as if it were boiling' there's surely a risk that the rig itself is gradually filling with gas and getting closer to the flare / anything else inside that sparks?
Certainly not an environment I'd want to land a helicopter in. Rowing boat with plastic rowlocks perhaps.
steveo - you're right, it's illegal to flare otherwise.
An issue I learnt about via Amnesty International was the quantity of gas being flared in the Niger Delta (principally by Shell). Apparently ~70,000,000 m^3 are flared each year (25% of the UK's total gas consumption). It's been illegal in Nigeria for years...
Presumably it's not worth the effort for Shell to store and transport the gas? Does this mean gas is too cheap?
I'm not sure what the most important issue is: wasting of resources? local pollution? or the larger climate-change it causes?
Locally in the Niger Delta, oil spills sound like the most serious issue though...
Yeah I read that too, Gas is cheap because it's not particularly useful not in the same way crude is. Its difficult to transport and seriously dangerous again unlike crude. Few countries in the world have the UK's natural gas network, to the point where the UK is amongst a very small group of destinations for LNG (Liquified Natural Gas) exports.
The facilities to liquify gas are expensive, the boats to ship it are expensive and the de-liquification plants are also expensive and quite rare. Only where there are pretty massive reserves of LNG would these be considered (Qatar).
There were big fears around the LNG transport ships in the communities near Milford Haven when the new facility was built. If one of them went up the explosion would make the oil refinery down south a couple of years ago look like a barbeque.
Environmentally, flaring is probably the better option if there is no local market. Carbon is less of a problem than methane and at once used it would be carbon any way.
I agree flaring is better than just spilling the methane directly into the atmosphere.
In terms of energy: recovering that methane and using it would still be worth it (even with the cost of storage and transport) but it is expensive, etc.
Although not many places have quite our gas network, a lot of places could do with a gas-fired power station or two... But Nigeria is a long way from anywhere that uses lots of electricity...
I'd suggest reading Frozen Fire by FoE regarding heavier 'petroleum' gases.
I would be a bit scared about a blanket of flammable gases lying colourless and odourless and spreading over a large area. You might read up about Los Alfraques where around 200 people died IIRC
In some ways the best action you can take in a major gas leak is actually to set light to the escaping gas and burn it up before it gets spread around and likely to go up in a less predictable way. Several folk who work with LPG (the really hairy stuff that you can drown in (heavier than air so it fills up depressions and the pits used to work under vehicles) say that the best thing to do if a tanker gets punctured is to strike a light before the stuff spreads over a huge area.
CNG on the other hand is methane and goes upwards to disperse. When a CNG bus depot had a fire the damage from the gas burning was a fraction of the damage caused by the water used to put out the flames.
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