As with all of us, I'm horrified and fascinated by the Gulf oil spill disaster. I keep trying to find a realistic understanding of how bad the disaster actually might be.
This short diary is intended to give a quick reference guide to the various units being discussed in reference to the Gulf oil disaster.
Crude oil is generally measured in tons, barrels, or gallons. There has been confusion in the media (and here) due to imprecision about these different measurements.
Tons. In brief, 1 ton of crude oil = approx. 7.3 barrels.
Barrels. I barrel of crude oil = approx. 42 gallons.
Gallons. Therefore, 1 ton of crude oil = approx. 306 gallons.
One site introduces the subject like this:
Crude petroleum, and the refined products made from crude oil, are normally
measured either by volume in gallons and US barrels, or by weight in tons or tonnes. The relationship between volume and weight is usually measured by density in the United Kingdom (the alternative measure is relative density or specific gravity). American oilmen usually reckon quantities of oil produced, moved or processed in barrels per day (bpd
or b/d). The loose but simple rule of thumb for conversion is that a barrel a day is roughly 50 tonnes a year, but the relationship varies according
to density and so according to product.
Source: http://www.eppo.go.th/... .
I went looking for this, because if you search for lists of major oil spills, they variously give units in tons, barrels or gallons.
As we know from many fine recent diaries, the estimated rate of leaking from the current disaster has steadily escalated from zero to 1000 barrels/day to 5000 barrels/day to the current understanding that it's now a minimum of 25,000 barrels/day, and possibly getting much worse as high-pressure grit in the upwelling oil erodes the pipes and machinery still in place. It may well turn soon into a full-blown gusher.
We must hope that they get supremely lucky and actually manage to cap this monster in three months, but I think that's unlikely.
Nobody knows the size of the deposit that has blown out. The entire deposit won't necessarily blow out, because at some point the upward pressure will be equaled by the immense pressure of one mile of ocean water. Gulf oil rigs routinely produce 60K barrels a day. This deposit is almost certainly in the tens of millions of barrels, maybe more.
There is quite a bit of variance among various Internet lists of major oil spills. Here is one good one which tries to show the top 10 spills in history:
http://envirowonk.com/...
The worst-case scenario here seems to give this blowout a realistic potential to be the worst oil spill in history.
Suppose the daily geyser is already at 50K barrels/day, or soon gets there, and sustains that rate. This is plausible. It is routine for Gulf oil rigs to pump out more than that every day.
That equals 2,100,000 gallons/day.
And now suppose that this goes on for an entire year. (The previous biggest blowout in the Gulf, the Ixtoc 1 field in Mexican waters, which were much shallower, took 10 months to cap.)
That equals 2,100,000 x 365 = 766,500,000 gallons, which is equal to 18,250,000 barrels. It's clear that BP thinks this reservoir holds at least "tens of millions" of barrels.
The biggest oil dump in history was Saddam Hussein's deliberate dump during the First Gulf War, which the link above estimates as 520 million gallons.
This one has probably already rocketed past the Valdez disaster, and possibly could go on to be the worst in history.
But hopefully there will be a lucky inspiration.
Surely the scientists and engineers can come up with better than this!
As I keep saying, I just can't understand how the oil companies don't have better fail-safes when there is such an astronomical amount of potential liability!
P.S. I'm not very good at tags. Feel free to add some better ones!