using US production as a model for global production is invalid because the US is not a closed market system: US production is price sensitive (+), so US production responds to changes in world prices, and thus declining US production is NOT a reflection of absolute limits on US supply, but rather a consequence of competition with low-cost foreign producers.  

It's like saying that the decline of the US consumer electronics industry is a model for the impending decline of the global consumer electronics industry.  Except that, quite obviously, US electronics makers declined because they have been under-cut by low-cost foreign producers and protected "national champion" electronics firms, first in Japan, then Korea and Taiwan, and now China.  And, equally obviously, total production of consumer electronics has and will continue to rise.

JLA offered good comments, which I responded to there.  In particular, he pointed out that if competition from cheaper oil sped up the decline following the 1970 peak (i.e., from 1970-1973), the high prices in 1974-1985 should have led to a resurgence in US production.  As I noted - that's what in fact happened.

I think perhaps a way to moderate the mutual distrust of the geologists and economists is to view the market for oil as having distinct segments: $10 oil, $20, $40, $80, etc... (in inflation-adj. constant dollars) They replace each other.  They exist in different quantities, in different locations, and peak at different times and rates.

$10 oil peaked decades ago.
$20 oil peaked very recently.
$40 oil is only starting to be developed (again - it's first heyday was 1979-85).

As a result, while the depletion curves for a specified price may be accurate, you'll have to consider the effects of rising prices on total oil production.  While field depletion in a constant-price environment - recent North Sea, US 1970-73, etc., may be steep, global depletion in a rising price environment will be MUCH slower when it happens (and the transition to declining production may consequently be quite far off).