IIRC, Deffeyes argument is that the geology of petroleum is well established science and he suggests that if there are any unknown major reserves, the only likely place is the S China Sea. His guestimates are subject to this assumption.
As for the industry's interest in arguing depletion for tax breaks and fewer regulations, there's also the interest -- recently exhibited by Shell -- to exaggerate reserves in the interest of stock prices and what-not. It doesn't all go just one way, although the interest to downplay is probably much greater than the interest to hype it up.
But leaving aside the technicalities, my original question was whether the policy people buy this. Is there any evidence of this, any scenario building they have done as with global warming, or a coming war with China? And, if indeed, the only likely unknown reserves are in the S China Sea, what then can we expect to see re the global geo-politics of this region, other than what we already see in terms of intra-regional competition over the tiny pieces of rock dotting the place?
None of this has to be malthusian. Indeed, that may be a misapplied label: petroleum, unlike say, human beings or food output, is not humanly produced, subject to fairly rapid shifts. Sure, there can be substitutes for petroleum -- but if indeed we are looking at peak oil, with neither China nor India anywhere near their potential demand, then it would also seem evident that, with the exception of nuclear, there is no feasible technology in sight that can kick in sufficiently rapidly. What then would be the socio-political consequences, both intra- and inter-country? Also, isn't one of the peak-oil analyses not that there will be a sustained rise in prices in the near- to medium-term, but of oscillations -- which, going by what happens even in the relative short-term of financial crises, can wreck considerable havoc?
kj khoo