Since there has been no drilling in ANWR, where are you getting your information on the reserve? I am curious, because I see that six month figure quoted all the time, but i can't ever seem to find a source.
My sources are actually not ones that would hold up in court. I haven't been in the field for a few years myself, but I keep in touch with my old workmates, and they are my "source." A couple of them in particular are pretty plugged in on stuff like that, so it's a case of "If Bob and Frank say it's true, then it must be true" for me.
Like I said though, I would be happy to be proven wrong, since I don't have any hard sources that I am citing myself. Like you, I would love to find some hard info on it. But I do know that there are advanced technologies now that enable us to guesstimate subsurface resources w/o having to drill. LandSat technology can do mineral exploration from space, w/o ever walking the ground or taking a sample. And there's always GeoPhysics... don't need to drill for that. Or just simple mapping of the formations, which can provide estimates based on previous knowns. You know the drill (pun intended)... Drill here, strike oil. Drill 10 miles away, strike oil. Formations are consistent in both wells... means there's a darn good chance you'll strike oil if you drill halfway between them, etc.
So, no, I don't have any personal knowledge of the data that was used to conclude there are only 6-months worth of reserves. I am just trusting my Geologist friends who follow these things. :-)