This is not a response to GilFriend, it is a comment for this post and the following one.

This issue, and making political hay of it, relies on most people not understanding the term "reserves." One tracking metric used by oil and gas companies is known as the R to P ratio, R/P. This is the ratio of proven reserves to current production rate and is expressed in years. If a company has 100 million barrels of oil on the books as proved reserves and produces 10 million barrels per year, its R/P would be 10 years. Most companies have an R/P of 10 to 15 years. Carter may have been technically correct at the time, but what was said was intentionally disingenuous. On the basis of proved reserves only, we have been 10 to 20 years away from running out of oil since oil was found to have significant commercial value early in the last century.

Reserves fall into 3 categories: proved, probable and possible. Proved has the highest certainty, greater than 90%. Probable and possible reserves have lower certainty of being recovered at the time the estimate is made. These estimates are updated frequently; annually for most companies. As work is performed in the fields, the certainty of recovering more or less oil than originally estimated changes. For most fields the total oil to be recovered increases as more wells are drilled, additional technology is applied and knowledge is gained. This increase is somewhat offset by the year on year production. Additionally, most fields assume a declining production profile as soon as development is completed.

This physical reality, the overall decline of existing reservoirs, is key to understanding that wells must be drilled each year to maintain production, much less increase it. Many fields have a long life: many still producing have been doing so for several decades. But a field that has a life of 30 years still has declining year-on-year production and this decline must be offset by new "reserves" every year.

The bottom line is that in most years, the annually recalculated defined proved reserves have more than offset the world's production. Production has grown to meet demand and yet proved reserves still have a 10 to 15 year life. There are sufficient reserves in all certainty categories to allow us to maintain current production for decades to come.

We still need to find additional deposits of oil and natural gas. It is still true that there are large areas of the world that have not been explored yet that likely have large deposits of oil and gas to add to our resource base. Due to massive advances in engineering and geologic understanding and application, these areas can be explored and developed safely, with a tiny physical and environmental footprint.

Well, assuming we keep using oil, we will eventually use up all th naturally occuring oil. Surely you don't dispute that?

Of course, that is probably still several decades (or more) away, but the statement itself (we are running out of oil), assuming they mean only naturally occuring oil (it can be produced in the lab!), is actually accurate.

What they IMPLY with that statement is another matter entirely...

I do dispute that we will eventually run out of "natually occurring oil." Much like oil (refined kerosene) replaced rendered whale fat for lighting, oil will be replaced by something else when the correct economic incentives apply. Useful oil "produced in the lab" is woefully uneconomic at this time, much like hydrogen is (way more energy is consumed in producing them than is contained in the result). Research must continue, with the resulting products competing in an open market.

We can't run out of oil because we don't know how much there is yet. Ever better exploration technology and human ingenuity is still finding new deposits and large potentially prospective areas of the world are still unexplored. We are finding new (and extending existing old) fields in heavily explored areas. It is correct to say that cheap to produce, easily found oil is being found less and less often. However, technology and human ingenuity will continue to find energy, given economic incentives and an open market.

An example: Canada's tar sand oil (thick, viscous oil found near the surface) can supply our need far into the future. The economics are not quite there yet but the research is continuing and we are getting several hundred barrels per day from them in the meantime.

Sorry. Last sentence should read "...several hundred thousand barrels per day..." What a difference a word makes.