The reason oil could drop as low as $20 per barrel

(Reuters) - How low can it go — and how long will it last? The 50 percent slump in oil prices raises both those questions and while nobody can confidently answer the first question (I will try to in a moment), the second is pretty easy.

Low oil prices will last long enough for one of two events to happen. The first possibility, the one most traders and analysts seem to expect, is that Saudi Arabia will re-establish OPEC’s monopoly power once it achieves the true geopolitical or economic objectives that spurred it to trigger the slump. The second possibility, one I wrote about two weeks ago, is that the global oil market will move toward normal competitive conditions in which prices are set by the marginal production costs, rather than Saudi or OPEC monopoly power. This may seem like a far-fetched scenario, but it is more or less how the oil market worked for two decades from 1986 to 2004.

Whichever outcome finally puts a floor under prices, we can be confident that the process will take a long time to unfold. It is inconceivable that just a few months of falling prices will be enough time for the Saudis to either break the Iranian-Russian axis or reverse the growth of shale oil production in the United States. It is equally inconceivable that the oil market could quickly transition from OPEC domination to a normal competitive one. The many bullish oil investors who still expect prices to rebound quickly to their pre-slump trading range are likely to be disappointed. The best that oil bulls can hope for is that a new, and substantially lower, trading range may be established as the multi-year battles over Middle East dominance and oil-market share play out.