I am going to keep this question really basic because I don’t even know enough to write a detailed, in depth question. I was thinking about oil production today and I suddenly realized that I don’t know how oil got deep underground in the first place. I have always heard the main theory was that oil was decayed organic material from millions of years ago. If that is the case, then how did the oil get so far underground. I realize that the surface of the earth is a changing thing but I can’t figure out how the oil got burried so far down in some places. It can be down thousands of meters.
The top of Mount Everest is limestone. That’s a sedimentary rock. It’s currently twenty nine thousand feet above sea level. It started out deep enough to make calcium dissolve from pressure of the ocean above it. It got to where it is now in a lot less than a billion years. Most of the rock on the surface of the earth is much less than a billion years old. It’s new rock. Life may be as much as three billion years old, so that leaves a lot of time for organic material to get deposited in places, and have more deposits pile up on top.
No expert here, but here are some excerpts from Time Magazine, Sept. 9, 1985:
“…Yet little hard evidence supports this conventional wisdom… It is simply a theory that is generally accepted…
As an astronomer, Gold approached the puzzle with a fresh perspective… Gold believes that when the primordial gaseous swirl condensed into the sun and its satellites, large amounts of hydrocarbons settled in the earth’s interior… He predicts that if greater depths were mined, fuel reserves far beyond current estimates would be found”.
Prediction confirmed.
Personally, I think Gold’s theory is logical and easier acceptable.
And in twenty years none of the oil companies have followed up with any reported success. Unless they are just sitting on these humungous hydrocarbon reserves until the price goes up more… (Wait, I know. Not a single oil company will release a gallon of these deep reserves until they have sucked every last drop out of Alaska, the Middle East, and Antarctica. Then, when we are all accustomed to paying twenty dollars a gallon they will start “finding” new resources and still charge us top dollar.)
Sorry, I don’t buy it. Human greed would have led to the exploitation of these oceans of petroleum by now if they were anywhere above the Moho.
I’m one of the board’s resident experts (a professional oilfield geologist).
How did all that oil get so far underground? It’s just a matter of patience. The Mississippi river drains almost of the rainfall of the Mid West out into the Gulf of Mexico. Along with all that water, there’s a whole bunch of sediment (sand/mud etc). It all settles down onto the seabed. Let’s say that 1mm (just 1/25[sup]th[/sup] of an inch) of sediment is laid down each year. After a thousand years, there’s a meter of sediment. After a million years, there’s a kilometer. After 10 million years, there’s ten kilomters (six miles) of mud piled up.
Hmmm…couldnt have put it better myself!
And so…after a few BILLION years, the oil is to be found - several miles below the surface of the earth by very rich, very well equipped oil companies with very long, very strong drills!
It should be noted that not all oil naturally occurs miles below the surface. Some of it actually bubbled up onto the surface, or became bound in rocks that were exposed to the surface by erosion. Most of the near surface oil oxidized, evaporated, or was used up in the first few decades of human oil consumption. After that, we started drilling. Then we drilled deeper.
You’d think that there’d be a kiddie level review of audi Arabia’s oil geology somewhere on the internet. I looked, and the best I found was this: Basement tectonics of Saudi Arabia as related to oil filed structures
It contains way too much information, but most of the basics are there.
Biomass under high pressure converts to a more compact, liquid form, which itself tends to seep and settle in underground basins. Saudi Arabia (and the nearly lifeless continent of Antarctica) were both once teeming jungles.
Whether abiogenic petroleum theory (or abiotic oil) really explains the existance of petroleum reserves and accurately predicts the existance of deeper and/or renewable petroleum sources is an unanswered question, methinks, though it is clear that other fossil fuel sources (coal) are of biogenic origin.
Sage Rat, the name you’re looking for is Thomas Gold. Far from being a crackpot conspiracy theorist, he was a respected if controversial physicist. This doesn’t make him right–he was a supporter of the now virtually universally rejected “steady state hypothesis” of cosmology–but he’s not pimping for Reynold’s Aluminum Corporation, either.
I personally think it’s an area that is open to further research and investigation but I wouldn’t go putting up the family savings bonds against future profits. IMHO.
“As an astronomer, Gold approached the puzzle with a fresh perspective… Gold believes that when the primordial gaseous swirl condensed into the sun and its satellites, large amounts of hydrocarbons settled in the earth’s interior… He predicts that if greater depths were mined, fuel reserves far beyond current estimates would be found”.
The conventional understanding most of us have been provided with sees two (at least) problems with this.
First is that apparently he’s depending on igneous reservoirs to hold this oil, the only kind available after the “primordial gaseous swirl condensed”. Generally speaking, that’s pretty poor rock to trap or extract any oil from. Far better reservoirs occur when that igneous rock is weathered over time into first sedimentary and then metamorphic layers, both potentially possessing not only the likelyhood of increased porosity, but permeability as well.
Also, conventional thinking is that oil is from a biogenic origin and, therefore, none could exist until after life appeared on Earth. You’d at least need plant development and preferably aboundant marine fauna as well. Therefore, except in rare cases (and there are some) you’re not likely to find much oil in Precambrian or other very ancient sediments.
I do realize Gold is taking a “fresh approach”, I just don’t much think he’ll have much to brag about in his completion rates.
Wouldn’t that mean that the seabed is now ten kilometres higher than it was 10 million years ago? If so shouldn’t it now be higher than the land it surrounds?
Are you saying the ocean once coverer Mt. Everest??? Now, I’ve heard everything… Is there a cite for this? (And, where did all the excess water go?)
Those scientists and their theories…
He’s saying nothing of the kind. There’s a (relatively) fixed amount of water on the Earth, certainly not enough to cover the planet to the depth of five miles.
No, he’s saying that the rock that is NOW at the top of Mt. Everest was FORMED at the bottom of the ocean. It’s on the top of a mountain now via the magic of uplift and plate techtonics: when the mountain range was thrust upward by two continental plates colliding (or whatever – there are a few different ways to raise mountains, not counting “really big wheelbarrows”), the rock was moved.
Or, if you prefer, you could say “yes, the ocean once covered Mt. Everest, but it wasn’t a mountain then.”
He’s simplifying. There’s a relatively fixed amount of sedimentary material; for it to accumulate at point A, it must have eroded from point B. The conditions that make it possible for sediment to accumulate would be changed by the accumulating material, eventually causing the accumulation rate to slow, and possibly reverse.
Also remember that there are a bunch of major and minor continental plates pushing each other around. When two meet, one is often pushed underneath, thus causing the sediment in that rock to be deeper than just accumulation distance. The actual location of oceans and land move around over such long periods of time; the earth’s crust is basically being “stirred” by plate techtonics.
[sup]Saudi Arabia is sand, not mud.[/sup]