Hydrocarbon Formation at Depth

I think this got mentioned on this week’s Skeptic’s Guide to the Universe in the science or fiction. I thought it might be the fiction, but wasn’t all that surprised when it turned out to be science:

Hydrocarbons in the deep earth (press release…?)
Stability of hydrocarbons at deep Earth pressures and temperatures (PNAS article)

And this of course ties back in to my previous linking and random ruminations about abiotic oil.

Mostly, I think this article is interesting, but not something explosive in terms of what we know about the formation of petroleum. I actually found this PNAS article via a post with the faceplam-worthy title “Oil and Gas Forever?1 on the website of The Global Warming Policy Foundation – which is apparently supposed to be “devoted to challenging conventional wisdom about climate change.” I do think that if you just check the front page of the site (The GWPF’s, not the Daily Mail’s), the axe they’re grinding is evident. Though maybe it is with the Daily Mail’s too, I wouldn’t know.

But I digress.

Despite the murky chain of links I followed to find the little PNAS article, I think it’s interesting. And will probably be horribly misused by excited people who think “Oil and Gas Forever” sounds like a lovely concept in general. The article itself is about computer simulations run to see if methane could form in to longer hydrocarbon chains at deep pressures and temperatures, and according to the simulations, the answer is yes. Which can be considered a point in the camp of abiogenic oil, but I would add the following cautions:

1) Whether long hydrocarbons can form abiogenically or not, that doesn’t in any way mean that all hydrocarbons – or even the majority – form in that way. Please see the bit about kerogens in my previous post.

2) This doesn’t really address any of the other questions important to developing hydrocarbons, such as: What’s the migration path, and how long does it take to get there? (And many more…)

3) It’s also not necessarily a realistic simulation. Quoting the first article:

“Our simulation study shows that methane molecules fuse to form larger hydrocarbon molecules when exposed to the very high temperatures and pressures of the Earth’s upper mantle,” Galli said. “We don’t say that higher hydrocarbons actually occur under the realistic ‘dirty’ Earth mantle conditions, but we say that the pressures and temperatures alone are right for it to happen.

Emphasis mine. So, like much science that gets slapped with melodramatic headlines, this is more of a, “Huh, that’s interesting,” than anything else.

1 – Actually, it’s not what you’d imagine out of an article with that title… it’s just the LLNL press release, and a C&P from a blog post that also pretty much emphasizes that there’s not really evidence for this being a major source of hydrocarbons, but that this is just sort of interesting.

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