Most U.S. producers seem equally uninterested in cutting production. Oil industry analysts say there are several reasons the decision to stop pumping when prices fall is not as straightforward as it may seem.

For starters, the cost of producing a barrel of oil varies widely from one well to another, based on the initial cost of finding and developing the oilfield, along with the costs of borrowing, operations and maintenance.

Some of the recent expansion of U.S. crude production, for example, has come from so-called "stripper" wells — once abandoned sites that are seeing new life thanks to advanced production techniques. Many of these are profitable even at current market prices.

But at $40 a barrel, roughly 2 million barrels a day of current global crude output costs more to pull out of the ground than it's worth, according to an analysis of global oil production by Wood Mackenzie, a commodities market research firm.