Is Bartlett's paper available on the web anywhere?
That I don't know. I have a hardcopy that he gave me at the ASPO-USA conference. I can fax or mail a copy of it to you if you can't find it elsewhere.
Here's a link to it.

http://www.hubbertpeak.com/bartlett/hubbert.htm
http://dieoff.org/page187.htm

and here's an interesting discussion of linearlization and Gaussians in a presentation:

http://www-physics.mps.ohio-state.edu/~aubrecht/AAPTSU02oil.pdf

So I'm not seeing too much insight in there into why it works. I can't believe this isn't well trodden ground.