Saturday, July 19, 2008

Questions about abiotic oil

This abiotic oil theory does seem to have annoyed some of you, although only one person has set forward any kind of scientific explanation as to why the abiotic theory is rubbish. Martin Meenagh pointed me in the direction of this Whiskey and Gunpowder report on why the abiotic theory is rubbish (by Byron King).

The evidence that he puts forward is basically five-fold, but has just raised yet more questions in my mind. If any scientists read this, I would be interested to know the answers to the questions posed: especially the ones about chirality. So, the evidence is this:
  1. Point: there is evidence that abiotic methane—required to form any abiotic oil—is manufactured deep in the earth. We see it coming up from vents underwater, and also seeping through the rocks in deep mines. However, there simply isn't enough to form the vast deposits seen in oil fields and the like.

    Questions: if large amounts of methane or oil are produced deep in the planet, the idea is that the majority of this then seeps through large, existing faults into the large underground caverns that we draw hydrocarbons from. Since this is the path of least resistance, then surely we would surely expect the vast majority of any abiotic hydrocarbons to end up in these wells, rather than seeping through deep, hard rock mines, etc. which are areas of higher resistance? How, then, can we decide that those expulsions that we do see show us that too little abiotic hydrocarbons are produced underground? And how do we know that these hydrocarbons are being produced at the same level as those that end up in the wells?

  2. Point: the transformation between abiotic methane and the many different long-chain hydrocarbons in oil is a massive leap chemically, and thus probably impossible as far as has been tested in lab conditions.

    Questions: the depths of the earth are pretty unknown territory: what do we know about such areas that allow us to deduce that such reactions—whilst vanishingly unlikely in lab conditions—are not entirely possible when considering such an environment and a still reasonably long timescale?

  3. Point: this is the point about chirality and optical isomers. Most hydrocarbons formed by organic processes shift polarised light to left, whilst most abiotic hydrocarbons shift said light to the right. Most of the oil found shifts polarised light to the left, and is thus organic in origin.

    Questions: why is this the case? It has been a long time since I studied organic chemistry (and I was very bad at it: had I not been, I would be a practising doctor by now) and cannot recall everything about chiral properties. However, is it not the case that these chiral properties are induced through the method of manufacture? Or is it the case that there is something inherently different about the carbon atoms in lifeforms on this planet that induce such a distinction in the organic carbon atoms themselves? Does this then mean that there are a limited number of carbon atoms on the planet from which all organic life is formed? Or, if it is the method of manufacture, what factors enable this distinction between organic and inorganic manufacture?

  4. Point: we know that organic matter can be carried deep into the earth's crust, because we have observed garnets within the pipes that diamonds appear in. The diamonds could only have formed at massive temperatures and pressures deep in the crust, but garnets could only have come from the surface.

    Questions: this is all true. However, a garnet is considerably more durable that the average organic body. Given the scraping of the tectonic plates and the vast pressures present when edges are subsumed, surely the organic matter would have to be in a rock-like state in order not to be simply scraped off onto the opposing plate? Is the organic matter then taken into the crust and turned into oil through massive temperatures?

  5. Point: we know that bringing garnets down through the Earth, forming diamonds and then spewing them up again takes a very long time but—look!—there's a star that probably exploded 440 million years ago. So things have been around a long time. Our planet is 4.5 billion years old and this is more than enough time to get some organic matter, pop it down into the crust and then bring it up again.

    Questions: this last bit is the silliest point, really. Although our planet has been around for some 4.5 billion years, organic life has probably existed for around 3.5 billion years. If we need special carbon atoms for the chirality argument, where did they come from? And if the chirality is based on the way in which the molecules are manufactured, where did the first chiral isomers come from?

    If the Earth has been around for billions of years, then why—even if abiotic methane seepage is as minor as posited here—could not have accumulated over that vast amount of time? After all, under the abiotic theory, the methane has had about 1 billion years extra to accrue and react than in the organic cycle (of course, if any abiotic route were that slow, then it's of little practical use to us right now).

I am not subscribing to the abiotic theory at all but I do believe that the explanations for why it could not happen this way raise an awful lot of questions. So, can anyone answer any of these questions? You have one hour and you may turn your exam papers over... now!

In the meantime, I am going to look at the organic formation method and raise similar questions about that. But first, maybe some politics...

14 comments:

Kay Tie said...

Complex organic molecules can come in two forms: left and right (so called because of the way they bend UV light). Life settled on one form only because the other form is incompatible as far as advanced enzyme reactions are concerned. Thus you can only digest left-handed (or laevorotatory) sugar molecules (for example), and not right-handed (dextrorotatory) ones. It's nothing to do with the atoms, but in the handedness of the molecules formed from those atoms.

And before anyone suggests using right-handed sugar for diet foods, it's been done. Right-handed sugar gives you the squits.

Devil's Kitchen said...

Excellent, thank you. Would this then lead to similar problems when trying to grow food in a lab? For instance, there has been some talk recently of using lab-grown meat rather than raising animals?

Or would you start with organic scraps and then be able to build onto those?

DK

Kay Tie said...

"there has been some talk recently of using lab-grown meat rather than raising animals?"

I don't know how that's supposed to work. Probably directly synthesising protein from source amino acids. The key is that different amino acid blocks are left-handed and not right-handed. The amino acids themselves will come from biological sources I expect (crops), so that'll be no problem. Personally I can't see the point of growing protein like that: it'll come out like Quorn probably.

Getting back to oil, you might remember from years ago a Tomorrow's World item on synthesising food directly from oil. How times have changed..

Johnny said...

Do a Google for "Thomas Gold" re abiogentic oil. He covers the issue of chirality. In fact, the problem for those who believe in the biogenic theory is that it's not uncommon to find oil that doesn't show the chirality expected due to biological origin. Other planets and moons in the solar system are awash with liquid hydrocarbons that can't possibly have a biological origin. What mystifies me (as someone with a degree in Biological Sciences) is why people are so wedded to the biological theories of the origin of oil and gas. Considering the solar system as a whole it seems to me that the theory that makes sense is the abiogenic theory. The proof will come if we ever make it to Mars, or Titan, or some other body in the solar system and find coal. Until then it appears we don't have the tools available to definitely declare which theory is correct.

Kay Tie said...

"The proof will come if we ever make it to Mars, or Titan, or some other body in the solar system and find coal."

Well of course there were trees on Mars: how else could they make the lock gates for all those canals?

Oxbridge Prat said...

Some partial answers for you. My training is in physical chemistry so I have a vague grasp of the general principles, but no detailed expert knowledge on this.

1) Movement of gas underground and its subsequent collection in oil and gas wells is not controversial. Indeed you pretty much need something like this to explain why so much helium is found in many natural gas sources. Thus the fact that gas and oil are present together is not proof of a common origin.

2) Abiotic production of methane is uncontroversial, though it is not clear how important a process this is. There are clearly identified reactions that would produce it which could occur under ground. And of course as others have been pointing out Titan is crawling with the stuff, and this has been ascribed to serpentisation, one of the putatitve routes to terrestrial abiotic methane.

Titan also has significant quantities of ethane and three carbon chain molecules, but doesn't have much beyond that. And that's the problem: there are no obvious abiogenic routes to long chain hydrocarbons.

We actually know a fair bit about likely conditions in the deep earth, and chemistry under those conditions, and what we do know indicates that cracking of long chains into short chains is what will occur, rather than building up short chains into long ones.

3) Chirality, people have answered above, and what they say is mostly basically right. The complex reactions of life require choosing one chiral form and sticking with it (it doesn't matter which one, and as far as we can tell it was just a 50:50 chance which one life as we know it ended up using, unless you believe some of the really nutty ideas about the influence of parity non-conserving nuclear interactions on the formation of chiral quartzes and clays). By contrast crude "chemical" reactions will normally produce and use both chiral forms at random (the exception is when they use complex chiral molecules as cofactors or catalysts, which is what life does). Thus the presence of a chiral preference in a molecular system is pretty much taken as evidence of life.

Oil contains some chiral markers, and this is usually taken as evidence of a chiral origin. Thomas Gold argued instead that the chirality arose because thermophilic bacteria were eating it and excreting in to it, and such contamination is hard to rule out.


To summarise: abiotic methane is uncontroversial, but is unlikely to be an important component. Abiotic oil is just about conceivable but seems wildly unlikely, and there is no significant evidence for it. Abiotic coal is simply nuts: the stuff is full of fossilized trees.

Devil's Kitchen said...

"Abiotic coal is simply nuts: the stuff is full of fossilized trees."

Well, that I know from my passing interest in fossil-collecting!

Thanks for that...

DK

Devil's Kitchen said...

P.S. I should point out that I do appreciate these answers. I have learned a colossal amount (mainly about economics) through blogging and I love the fact that there is more to know, and people to supply the answers!

My own scientific interests are rooted in the fields of genetics and pathogens (and my formal education was, anyway, over a decade ago), so this kind of chemistry/geology is a bit beyond me...

DK

David Davis said...

The abiotic theory, to me, hold water because:-
(1) there is vastly more carbon in terrestrial hydrocarbons than is present in the living biosphere. (There is also about 30,000 times more carbon in limestone and other buried carbonates in the crust, originating primarily from atmospheric CO2 which was far far far more plentiful than today.

(2) Methane, ethane and other hydrocarboins have been observed in huge amounts in space. There is also a lake of lliquid methane on Titan (go the http://strangemaps.wordpress.com) the size of the Black sea or even bigger.
(3) It's possible, under conditions present in the upper mantle and lower crust, to convert methane into long chain hydrocarbons. Natural gas (methane) available to us near the surface is thought to be due to "thermal cracking" of bigger hc's in the less violent conditions present where we find it.

(4) Chirality is likely to be an evolutionary accident, written into ROM (as it were) at the time comples biomoelcules were coming into being and self-reproducing widely, about 4 billion ysrs ago. All "naturally-occurring" amino acids (the lego of proteins) are "laevorotatory". Most other biomolecules with an asymmetric C atom are. GLUCOSE is NOT!!! As I said, it's a series of accidents.

(5) SOME of the reservsoirs of crude oil and gas contain molecules with Oxygen and (more usefully) Sulphur in them. In coal, it's obvious that the S atoms present have to be associated with biomolecules. But in oil and gas, I don't know what your sources say but to my miund this is not the case. Living organisms have a propensity to concentrate the isotope Sulphur-32 (lighter than S-34) because a higher rate constant for reactions involving it is achievable (ie the molecules are ever so slightly lighter and can move a teensy-bit faster). The same is true for O-16 versus O-18.

The debate about the origin of the Earth's hydrocarbons could easily be settled, IMHO, by examining the S and O isotope relative % contents versus what it is in living matter.

Anaconda said...

Crude oil is an ultramafic mineral. Ultramafic means its formation is in an environment of ultra-high heat and pressure. There are a number of ultramafic minerals: Diamond is a good example. Also, all minerals are subject to the rules of formation and dissolution constrained by heat and pressure. Different minerals form and break apart at different points on the heat/pressure gradient.

A good scientific paper that treats the "odd-even" issue is
Dismissal of the Claims of a Biological Connection for Natural Petroleum. Focus on J.F. Kenney's "odd-even" abundance claims discussion, it's technical I grant you, but so is this objection to abiotic oil.

The whole website is a "must."
Gas Resources corp.. J.F. Kenney is the leading abiotic oil geologist in the United States.

Also, the website
Oil Is Mastery is devoted to abiotic theory. It has many scientific papers hyperlinked -- the hard science is substanial and documented.

Several comments talked about the lack of hydogen and carbon in the Earth's interior to support abiotic theory: No, any quick check on mineral compositions show that there is plenty of carbon and hydrogen in the Earth's mantle to form petroleum.

There are over 4000 known mineral combinations. I have to ask this question: What is so surprising about hydrogen and carbon, which have an affinity for chemical (bonding) combination because of their atomic electron counts and placement, forming in the Earth's crust?

Particularly, when you remember hydrogen is the most common element in the universe and carbon is close behind.

When you think about it -- it's only natural.

Actually, what's ironic about the comments is that it's 'organic detritus' that doesn't account for all the oil that has been found.

When you picture petroleum as a mineral, a mineral with unique properties for sure, but which follows the laws of mineral formation and dissolution, then oil isn't mysterious anymore.

Anaconda said...

Dismissal of the Claims of a Biological Connection for Natural Petroleum.. My apology for the failed link.

Johnny said...

"Abiotic coal is simply nuts: the stuff is full of fossilized trees."

Which is exactly why coal on other planets would represent definitive proof of Gold's thesis.

What you have to explain meantime is why the fossilized trees are fossils rather than coal. Seems to me you've got some fancy footwork to do to explain why some trees turn into coal whilst some become perfectly fossilized, yet both in the same place.

OilIsMastery said...

Here is a website dealing with abiotic oil.

Anonymous said...

Oil and black coal are abiotic of course. Natural hydrocarbons are primordial materials that erupt from great depths. We are in XXI century, not in Middle Age. it's important keep in mind what said Sir Fred Hoyle:

"The suggestion that petroleum might have arisen from some transformation of squashed fish or biological detritus is surely the silliest notion to have been entertained by substantial numbers of persons over an extended period of time." — Fred Hoyle, 1982