There are many explanations for this, mostly down to location and population. For instance it is no accident that the US, Russia and Europe have developed oilfields in close proximity- that is where the major demand is. Plus the presence of stable government is a clearly a critical factor for development of any kind.  

Although there are rumours there is a North Sea size field in the Great South Basin (google for it) to the southeast of New Zealand, which has never been developed due to lack of capital and distance to markets.

You guys are correct- it just seems like an interesting fact I had never heard before.  
Much of the land in the southern hemisphere is Antarctica.  To have "biotic" oil, Antarctica would have had to experience millions of years of sustained vegetative growth, right?
Well, it did ... but is geologically unpromising in other ways, as far as I know.
There have been coal seams discovered in Antartica.  Several times in geological history Antartica has had abindant plant & animal life, but not for a majority of the time.

Perhaps there is oil in Antartica, but the repeated addition and removal of ice sheets should surely stress the geology of Antartica and I would not be surpriced if most of the oil did not escape after repeated "flexing" of the cap rock and associated fractures.

Antartica is a small continent.  Slightly smaller than Australia from memory.  So I have little hope for more than a trickle of oil from there by 2150.

Sheesh... that article is real tinfoil-helmet stuff. But then they're gold bugs, aren't they? Most of the world's land is in the North; most of the world's continental shelf; most of the world's sedimentary basins; hence most of the oil.

Look here >>> http://www.britannica.com/eb/article-50720