Abiogenic petroleum
Posted: 28 November 2007 07:31 PM   [ Ignore ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  459
Joined  2007-06-19

I was reading about the theory of abiogenic petroleum (and hydrocarbons in general).

I don’t have the knowledge to tell if this is a scientific theory worth to take it seriously or is just a convenient idea to support our world economy based on hydrocarbons. Do you have any idea about it?

Profile
 
 
Posted: 28 November 2007 11:28 PM   [ Ignore ]   [ # 1 ]
Moderator
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5508
Joined  2006-10-22

Since I’m a U.S. scientist, not a Russian one, I go along with the theory of biogenic formation of hydrocarbons.  When you consider the amount of oxygen in the atmosphere, none of which was here before the advent of green plants that converted the carbon dioxide to oxygen and carbohydrates, it seems reasonable that all those carbohydrates must have gone somewhare.  The theory is that they settled to the ocean floor, were covered over by sediment, and under the extreme pressure and heat were converted to hydrocarbons and water.  (that’s a pretty simplistic explanation, but it’s too much trouble to be precise and go on for pages.)

Occam

Profile
 
 
Posted: 10 December 2007 12:17 AM   [ Ignore ]   [ # 2 ]
Jr. Member
Rank
Total Posts:  6
Joined  2007-12-09

I heard of it as abiotic instead of abiogenic petroleum, but I think it is the same thing.

The proponents of abiotic oil that I have heard state that petroleum is produced deep in the earths crust or mantle by some unexplained process (the Keebler Elves maybe?) and slowly works its way up towards the surface.  So there is no reason to worry about depleting oil reserves.

The problem with this is, is that the we find petroleum in the areas where the biogenic model says we should.  If oil was produced by an abiogenic process, why do we find it in sedimentary and metamorphic rock formations and not igneous ones?

It also goes against what we know about hydrocarbon chemistry.  When hydrocarbons are exposed to high enough amounts of heat and pressure, they break into smaller chains.  This is the process called cracking, and is commonly used to make usable fuels out of heavier crude oil.  If enough heat and pressure is applied, the carbon chains will break down to the simplest hydrocarbon, methane, also known as natueal gas.

Since heat and pressure increase the deeper we go into the earth, petroleum would break down, not form.

Biogenic pertoleum formation has a whole lot more evidence to back it up.

Profile
 
 
Posted: 10 December 2007 03:00 PM   [ Ignore ]   [ # 3 ]
Moderator
RankRankRankRankRankRankRankRankRankRank
Total Posts:  5508
Joined  2006-10-22

You are correct Cthulhu.  And the next step in the breakdown would be to carbon and hydrogen.  That means all of the abiogenic material would be coal and there would be no oil, and not even any natural gas.  I haave a hard time imagining how coal would migrate up through hundreds of miles of solid strata and I don’t know of any hydrogen wells.  Besides, at the extreme pressures most of the coal would convert to diamonds or at least, graphite. 

Occam

Profile
 
 
Posted: 14 December 2007 12:36 PM   [ Ignore ]   [ # 4 ]
Sr. Member
RankRankRankRankRankRankRankRankRankRank
Total Posts:  459
Joined  2007-06-19

Thank you very much to you both.

The migration of coal up through the solid strata is a point I missed.

Profile