Other energy companies are testing the export waters on their own without explicit approval from the government for such sales. So far, roughly 3 million barrels of ultralight oil have been loaded onto tankers leaving Texas, and the energy industry expects that figure to grow in 2015.

Signs that the U.S. is starting to export its glut of oil is one of the factors that has sent global oil prices sliding by almost 50% to levels not seen since the most recent recession. U.S. crude prices also have tumbled to under $ 60 a barrel.

Whether they will rebound in 2015 is a question that has split energy analysts. Those who say China's economy is becoming less focused on manufacturing expect crude to languish in the $60 range, while a few optimists expect cheap oil to spur demand and are predicting a rebound to $90 a barrel.

As much as 80 million barrels of ultralight oil might leave the U.S. this year from the Eagle Ford Shale in South Texas, if prices stay competitive, said Sandy Fielden, energy analyst with RBN Energy LLC. Significant amounts of the oil pumped in West Texas, Oklahoma, North Dakota and even Colorado could also qualify for export.

Energy companies, including Pioneer, continue to lobby Congress for a full lifting of export restrictions. Supporters argue such a move would help create jobs and improve the trade deficit, but opponents question the wisdom of shipping American oil overseas while the country is still a major importer and consumer of foreign crude.

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