Asteroid hits oil field

What would happen if a big asteroid crashed down on an oil field ?

A very loud boom?

Seriously, the question depends on how big. Chicxulub impactor size is going to cause a global extinction event regardless of the geology of the impact site. You can scale down from there to an event that only damages the pumping equipment.

If you’re thinking about splashing flaming oil all over the place, remember that the oil in the field is deep underground, and won’t be affected by any hit except one that would be cataclysmic anyway.

Whilst it its a truism that all the easy oil and gas has gone - and thus the big deposits of shallow stuff, there are still going to be some deposits that might be cause for some fun.

There are a lot of difficult and shallow hydrocarbons - and just carbons (aka coal) that could be breached by a small impactor. The Canadian oil sands are perhaps the most significant. Here you have massive deposits of a sticky thick muck only a small distance below ground. A Tunguska sized impactor could easily breach a large swath of oil sands and set fire to the reserves causing a really nasty and difficult to control fire. Underground coal fires are really nasty too. One could probably imagine ways to start one with a small impact.

I think this is a little like asking what happens if you set off a nuke over a gas station. :slight_smile:

Yeah that sounds like the sort of calamity I was thinking of. Given that these rocks can smash kilometers into the Earth when they hit, wouldn’t that be enough to explode any sort of gas, oil or coal field ?
So it could vaporise the tar sands ?

The energy released by an meteor that creates a kilometer-deep impact is going to be vastly greater than the energy released by the burning oil.

Oil would go sky-high.

By how much ? Volcanic actvity burned a load of coal off in Siberia during the Permian/Triassic extinction, and caused a lot of global warming.
So could an asteroid do similar ? Granted asteroids are devastating on their own, what about long term fossil fuel fires or hydrocarbon vapor release ?

Consider the Ghawar oil field. It contains a good 50km[sup]3[/sup] of crude oil. Probably more. That is at least 1.5 x 10[sup]27[/sup]Joules. :eek:
This is after about half of the recoverable oil has already been produced. But it is about 2km down.

I had a play with the Purdue impact simulator. In order to get a transient crater to reach 2km down I had to use an iron meteor of 300m diameter, with otherwise reasonable parameters - 17kms[sup]-1[/sup] and 45º impact. The final crater is only 500m deep, but the transient crater will breach the Ghawar field. The impactor has an energy of 1.6 10[sup]19[/sup]J. So is 10[sup]8[/sup] less energetic than the field. But that is an extreme and contrived case. The Ghawar field is 280 by 30 km, if we consider that our mooted crater will be about 7km is diameter, we might assume we affect about that area of the field in some meaningful way, so about 0.2% of the field. However we are still at about 10[sup]5[/sup] less energy in the impactor than in the oil below impact.

With a more common oil field the disparity will be less, but I would say that we can think in terms of 1000 or 10,000 times as much energy in the oil field as in the impactor even for quite deep deposits. The Purdue simulator suggests we get one impact this big every 100,000 years.

So what happens? Still hard to say, but the environmental impact from blasting that much hydrocarbon out and setting fire to it in one go might be pretty significant.

That is why I was looking at the oil sands. A very much more common and low energy impactor could stir up something pretty nasty if we were unlucky. OTOH, there is a very good chance such a thing has happened more than once in geologically recent times.

An oil field can’t explode when hit by a meteor.

Remember the fire triangle. Fuel plus heat plus oxidizer. Remove any part of the triangle, and fire goes out. Explosives explode because they contain both fuel and oxidizer. When you provide heat–like, say, from a crashing meteor–the fuel chemically reacts with the oxidizer and you get a big boom.

But what chemical reaction happens when we just add heat to fuel? Nothing. Gasoline by itself can’t explode. Gasoline by itself can’t even burn. Gasoline needs oxygen from the air to burn, and it needs to be thoroughly mixed with air before it can explode in a movie-style gasoline explosion. To make gasoline explode you need to create gasoline/air vapor, and set that on fire. You can put out lit cigarettes in gasoline, and not get a fire. But when you set gasoline on fire it just burns, it doesn’t explode. To get movie-style gasoline fireballs they use an explosive to create a cloud of gasoline vapor and air, when they explodes nicely. Or they fill the car interior with gasoline vapor and set it off. But you have to carefully calibrate the fuel/air mixture, too little fuel and no explosion, too much fuel and no explosion.

Underground coal beds can catch on fire, and burn for years. This happens when air can reach the coal, and the coal gets hot enough to burn until all the oxygen is consumed. But because the fire is underground, the hot coals are often insulated and remain hot for a really long time, and can start burning again whenever more oxygen reaches them. So fires of this type are limited by the oxidizer leg of the fire triangle. You don’t get explody-type reactions except in cases where you have coal dust particles exposed to air that get heated to combustion temps.

In order to explode - or even burn you need to get enough oxygen to the fuel. You are simply not going to be able to do that. You might vaporise a lot of oil and release gas, but it will simply displace the air, and you will get a fire on the outside edge of the bubble. No kaboom commensurate with the amount of oil you are releasing. But a very long lasting fire may possibly result.

The kaboom will be no larger than if your impactor hit water and vaporised that.

Ha - ninja’d. :slight_smile:

My guess is that an asteroid impact would be energetic enough to pretty much instantly vaporize and burn up any hydrocarbons instantly, and without much effect. Kind of like putting a 1000 gallons of gasoline at ground zero in a nuke test. It would definitely burn up, but it would be so dwarfed by the nuke that it wouldn’t be noticeable.

A smaller meteorite could possibly set it on fire, or possibly mess up the geology such that it’s harder or easier to extract relative to the pre-impact geology.

I did a rough calculation that Ghawar reserves have about 13 gigatons of CO2 if it could all be burned, just counting estimated recoverable reserves (which are state secrets) and discounting gas.
It’s quite a lot. A big enough asteroid would pretty much release and burn all that through cratering, earthquake and shock. I think. Although the largest known Earth crater is about 190km diameter.

But the effects on the surrounding land don’t stop at the edge of the crater and I would think it would have disruptive effect on oil/gas reservoirs one way or another.

Burning all the tar sands would give 240 gigatons - several years of human activities worth. Don’t know what heat that would add to the atmosphere from combustion.

But yeah an impact that big would incinerate the forests anyway, probably globally.

I was thinking of a body a lot bigger than 300m - Chicxlub was around 10km I believe, but that very nice Purdue simulator doesn’t want to work for me :mad:

But those seem to be rare and chances are all oil would be consumed before such a strike. But it could happen tomorrow. We don’t know. It could be just entering our atmosphere right now…

Correction largest known crater was 300km when formed, but has eroded down to 190km. Big enough to wipe out Ghawar,

Great, that means we can test it!

If an area full of oil rigs was nuked would it set them all on fire ?

That’s a good question. I know that explosives are sometimes used to put out an oil rig fire - deprive the area of oxygen and the fire goes out. A nuke would certainly consume and/or push out all of the oxygen for a brief time, but it would probably leave a lot of hot surfaces and small fires behind that could ignite the oil. In a desert, residual fires would be less likely than in a forested, grassy or urban area.

One suspects that the result would be a good match to the situation in Kuwait after Iran left.

Keep in mind that oilfields aren’t just big underground pools of oil. The oil is in the pore space in the rocks, which for something like a typical sandstone reservoir rock may only be like 10-15% of the total volume of the rock. An oil reservoir isn’t going to just spontaneously burn on its own because there’s no good pathway for oxygen to get to the oil in the pores.

In the case of Kuwait after the Gulf War, that reservoir was under enough subsurface pressure that the oil flowed to the surface through the wells even after the pumping equipment had been shut off, and of course the oil only burned once it reached the surface. Most oilfields aren’t under enough pressure to flow on their own, though, (especially in these post-“easy oil” days) and so the Kuwait scenario couldn’t happen.