Pump jacks are seen next to a canal in an oil field over the Monterey Shale formation where gas and oil extraction using hydraulic fracturing, or fracking, is on the verge of a boom on March 23, 2014 near Lost Hills, California. - 

Ever since the oil crisis of 1973, when oil prices nearly quadrupled as a result of an OPEC embargo following the Yom Kippur War, there has been a ban on U.S. crude oil exports. But that may change.

In two rulings, yet to be confirmed, the U.S. Department of Commerce will allow two private companies to export a special type of crude oil. It's a tiny opening in what could be a big change for the oil industry.

The crude oil at issue is a specific type of lightweight crude called condensate. It’s very different from what you probably picture when you think of crude oil. Condensate is not the thick, black oil that came a “bubblin” out of the ground in the opening credits of The Beverly Hillbillies. Condensate is thinner, it can look like tap water, and it’s highly volatile.

“Condensate,” says analyst David Bellman, “is actually one of the crudes that would be the easiest to refine.” It would be the easiest to refine, if it weren’t for one problem. “The problem is that the refining industry, for the last couple decades, has been told that crude oil is going to get heavier and heavier,” says Bellman.

As a result, refineries invested in equipment designed for refining heavy crude. But since the fracking boom, 96 percent of new oil production is ultralight, not heavy crude. “It’s not a great fit for the refineries in the U.S.,” says Severin Borenstein, co-director of the energy institute at the Hass School of Business at Berkeley.

Oil producers are worried that this bottleneck could get worse, driving down the price of condensate. “So the argument they are making is, they should be allowed to export those crude products,” says Borenstein.

Industry analyst Fadel Gheit says lifting the ban would lower crude prices on the global market. But it would raise condensate prices in the U.S. That’s bad news for U.S. refineries, as evidenced by a dip in their stock prices today. “They had one of their worst days in years,” says Gheit.

There is no consensus among analysts on what lifting the ban would do to the price consumers pay for gas at the pump.

Follow David Weinberg at @@randomtape