The U.S. Commerce Department quietly has cleared two Texas-based companies to export a type of crude oil, slightly easing decades-old restrictions and possibly opening the door for many other oil producers.

The move comes amid debate over whether the export prohibitions should be reevaluated as domestic production booms.

The Commerce Department said in a statement that the approvals, first reported Tuesday in the Wall Street Journal, were not a change in policy. Oil producers are allowed to export processed petroleum products. Responding to requests from Pioneer Natural Resources and Enterprise Products, the department's Bureau of Industry and Security (BIS), determined that very light crude that has been only minimally processed could be shipped overseas without a license.

The decision is significant, but not surprising, said John Auers, executive vice president of Turner, Mason & Company, a Dallas, Texas-based engineering consulting firm that is studying the issue. "We were—I think other analysts were—[expecting] that what the BIS would do is sort of dip their toe into the water."

U.S. production of oil has been steadily growing in recent years, and with it calls for relaxing the rules on exports. Last month, energy research firm IHS released a report saying that lifting the effective ban on exports would reduce U.S. gasoline prices and boost domestic crude production by almost 30 percent.

IHS consultant Daniel Yergin called the current policy an "archaic remnant of a system that disappeared 33 years ago." Others, including Alaska Senator Lisa Murkowski and researchers at the Brookings Institution and Council on Foreign Relations, also have argued for an end to the ban. (See related story: "Amid U.S. Oil Bounty, a Growing Debate Over Exports.")

But supporters of the restrictions say that the policy protects U.S. consumers from oil price fluctuations. Senator Ed Markey of Massachusetts said in a statement Tuesday, "Congress put this oil export ban in place. It should be Congress that decides when and how to change it, not through a private ruling by the Commerce Department without public debate."

The Condensate Question

The current restrictions, which emerged in response to the Arab oil embargo of 1973, are not an outright ban. Oil producers can export oil under certain conditions-to Canada, for example, where U.S. exports have quadrupled over the past five years. Still, less than 2 percent of the oil produced in the United States is sold outside its borders. (Take the related quiz: "What You Don't Know About Oil Crisis History.")

The lightest grade of crude, called condensate, makes up less than 10 percent of roughly 8 million barrels per day of oil currently produced in the United States. Hard numbers are difficult to come by, partly because different entities define condensate in different ways. The Energy Information Administration estimated in a recent report that the United States produced 621,000 barrels per day in 2013. More inclusive estimates put that figure closer to 1 million barrels per day. (Vote and comment: "How Has Fracking Changed Our Future?")

Often a byproduct of natural gas production, condensate can be refined into motor fuel or other products, such as naphtha (used in making chemicals) and kerosene. Those products are not subject to export restrictions.

The Commerce ruling will allow the export of condensate that has been "stabilized," or run through a distillation tower to remove volatile components so the oil can be transported in a pipeline. Many producers in the Eagle Ford shale in Texas could take advantage of the decision because they have the capability to do this minimal processing as part of readying the crude for transport.

Questions about how much condensate is being produced, and whether it can be exported, have been complicated by a lack of consensus about definitions. "Condensate is really a widely used term and can mean a lot of different things," said Erika Coombs, an analyst with the energy market analytics firm Bentek, based in Denver, Colorado. She also noted that the same issue applies to processing, saying, "The regulation says anything processed can be exported, but what does processing mean?"

"A Story That's Still Developing"

With at least part of that question clarified, the door is now open for many oil producers, particularly in Texas, to seek new markets for condensate that is selling in the United States at a discount.

Several companies already have invested in facilities called condensate splitters, which can spin off exportable petroleum products from very light crude. But if producers can export their condensate with just a minimal amount of processing, raising the price in the process, the economic viability of some new splitter projects will become less clear.

"We've seen a stall in condensate splitter project announcements in 2014, and it has been because of all this uncertainty around the export ban," Coombs said, adding, "I wouldn't be surprised if we see some of these projects that are in the early stages of planning stall because of this announcement."

It is not clear how much U.S. condensate might be exported, or how high the global demand is. "This should strengthen the price of condensate because it gives it another outlet," said Turner, Mason & Company's Auers. "How much, I don't know. It's a story that's still developing." He said potential markets would include Asia for the petrochemical industry and South America, which could use condensate to dilute its heavy oil for pipeline transport.

A formal change in export policy is unlikely to happen before midterm elections in November, experts say, but Energy Secretary Ernest Moniz has signaled a willingness to reexamine it. In the meantime, the debate will continue.

Part of the pressure to allow exports is coming from oil producers who have limited channels for their light crude, given that U.S. refining capacity is tilted toward accommodating heavy oil from Venezuela, Mexico, and Canada.

On Thursday, a House of Representatives subcommittee will hold a hearing on "the mismatch between the supplies of oil produced and the capacity of the refining sector to manufacture it into useful products."

Auers called the Commerce decision "a very politically safe step." He said it remains to be seen whether the move will ease some of the domestic glut of condensate and the calls for increased exports: "Everybody's going to see how this works, and does this relieve the pressure at least for some period of time," he said. "I think that's the hope of the administration."