[Dreamtwister]

At what level of consumption is oil use sustainable?

Let's use the high-end estimate of world total OOIP (I can't remember where I saw it, but I think I saw 2400 billion was the most pollyanna fantasy land figure out there)

If we start counting from the Cretaceous-Tertiary extinction event 65 million years ago and counting up until the present (pretend 100% extraction is possible, oil genesis is linear and there are no other variables), then the most optimistic figure would appear to be:

2,400,000,000,000 / 65,000,000 = 36,923 bbl/yr or 101 bbl/day WORLDWIDE.

However, if we start counting from the beginning of the Triassic period (230 million years ago):

2,400,000,000,000 / 230,000,000 = 10,435 bbl/yr (rounded up for even more optimism) or 28.6 bbl/day WORLDWIDE.

If we begin counting from what is believed to be the beginning of life on this planet roughly 4 billion years ago:

2,400,000,000,000 / 4,000,000,000 = 600 bbl/yr or 1.64 bbl/day WORLDWIDE.

Anything exceeding the figures above would cause depletion, because consumption would be higher than genesis (I'm hesitant to call it "production").

Of course, this is all very simplistic. I think we can all agree that 100% extraction will never happen, oil genesis is not linear, and there are certainly other variables. I think the OOIP of 2400 billion bbl is also likely to be highly optimistic.

Any thoughts?

[Gazzatrone]

I think you have to grasp the fundemental principle that there is NO sustainable level of consumption of a finite resource. However much you use you will eventually run out.

[mekrob]

But oil is a renewable resource. There is constantly more and more oil being made, its just that the rate of production (actual production) is just so low. Either a few thousand barrels a year (abiotic) or with fossil fuel theory it would be a few million barrels a year. Either way, we can't have our current society, but even 1 mp/y is pretty nice as it is good for making plastics, meds, etc.

[zoidberg]

I read that the oil sands are like pre-oil oil. So it would seem we are robbing not just the current store of the stuff, but also the next few hundred million+ years of it as well.

Therefore there is no sustainlable consumption level. And even if it was springing up from the bowels of the earth, we need it nicely concentrated before we can effectively extract. Cant drill a well for a few liters of it.

[mekrob]

$this->bbcode_second_pass_quote('', ' ')I read that the oil sands are like pre-oil oil. So it would seem we are robbing not just the current store of the stuff, but also the next few hundred million+ years of it as well.

[Etalon]

Considering we have used up about half of the oil that is currently in the ground (ish) in say 100 years and that it took of the order of a billion years for it to be produced, using my very rough +- order of magnitude calculation, that means:

1 billion years / 200 years= 5,000,000. That is how many times above oil production rates we are extracting it ( very, VERY roughly).

What we on, 80 million barrels per day? Divide that by 5,000,000 and we get... 16 barrels per day oil production. Now, this calculation is probably totally wrong, BUT it gives you an idea on what we are dealing with.

[fluffy]

Remember that in many situations, oil trap structures underground are 'filled to spill'; i.e. they reach the point where any additional oil simply escapes to the surface. Much the same way as a lake can only fill so much before water finds a way out.

This means that oil generation rates (and reservoir refill rates) are much higher than a basic calculation as above would suggest. Some reservoirs could refill in just a few tens of thousands of years; of course, others would never refill since their source rocks are over mature.

[Madpaddy]

Etalon wrote;

$this->bbcode_second_pass_quote('', 'W')hat we on, 80 million barrels per day? Divide that by 5,000,000 and we get... 16 barrels per day oil production. Now, this calculation is probably totally wrong, BUT it gives you an idea on what we are dealing with.

[GreyZone]

Your error is in assuming that the oil in place when humans began extracting it is all the oil that ever was. This is not true. Oil and natural gas constantly escape and are absorbed into the greater ecosystem. Plus oil formation can occur relatively rapidly on geologic timeframes. For example, I believe the Brazilian offshore fields are only a few tens of thousands of years old but had ideal conditions when they formed.

I am not sure you can model oil as simply as the OP has done. Climate has changed radically since the very tropical period of the far past and plant growth is not the same as then (though maybe global warming will change that). One factor in recent climate change (recent, as in geologic terms) was the onset of regular and recurring ice ages during the pleistocene period. There remains speculation about why this occurred but one theory says that the rise of the Central American isthmus a few million years ago ultimately caused a change in ocean circulation patterns, disrupting a prior heat exchange system that kept the planet generally on more even climate terms from the equator to the poles. The emergence of that isthmus cut off that circulation, forcing the ocean circulation to emerge in new patterns (the modern thermohaline circulation). The result is that the formation of oil bearing rock may now be much harder (or possibly much easier - who can be sure?) than prior eras. Thus, for both of these reasons, I don't think you can model oil creation as simply as the OP has done, which makes the assessment rather useless.