On Tuesday, West Texas Intermediate was trading just above $100 per barrel, while Brent, the international benchmark, was just above $107 per barrel.
"I look at what crude oil on the Gulf Coast is trading at relative to crude oil at Cushing," said Lipow. "It's only 50 cents to a dollar more than Cushing, which does not pay for the pipeline tariff and that's an indication of glut appearing on the Gulf Coast."
The U.S. still imports oil—7.6 million barrels a day last week, but the source of those imports are changing. Canada remains the biggest supplier and Saudi Arabia is second, but African crude is losing ground. The U.S. imported just 34,000 barrels a day of Nigerian crude in January, down from 300,000 a year earlier. In 2008, the U.S. imported 9.8 million barrels a day.
"I think you're seeing a reconnection of the North American market with the Atlantic basin Brent," said Eric Lee, analyst at Citigroup.
Lipow said U.S. refineries are using more oil and are exporting more refined product to the world market. Crude exports are largely restricted, and there have been increased calls to export to Europe because of the situation with Russia, a major source of European oil and gas.
Lipow said U.S. oil has displaced Gulf Coast imports of light sweet crude from Nigeria, Libya and Algeria. "As the buildout of crude by rail to the East Coast gets completed, we will displace all imports of light sweet crude into that region by the third quarter of this year," he said.
—By CNBC's Patti Domm.