Though data suggest crude oil production is on an upward trend, the number of drilling permits in Texas dropped more than 3 percent, regulators said.

The Texas Railroad Commission said crude oil production in October, the last full month for which data are available, averaged 2.2 million barrels per day, a 25 percent increase year-on-year.

Texas hosts some of the largest shale oil basins in the country and remains the No. 1 producer in the nation, besting the No. 2 state, North Dakota, by a wide margin.

The slumping price of crude oil is putting pressure on producers working in some U.S. shale basins. Prices are near the point at which production in the state's Eagle Ford basin may no longer be profitable.

In terms of permits, the Texas regulator said it issued 1,508 original drilling permits in November, compared to the 1,559 issues in November 2013. Of those, most were new drilling permits.

The U.S. Energy Information Administration, a division of the Energy Department, said the increase in drilling and improvements in drilling efficiency have led to more oil from the Eagle Ford shale region in southern Texas.

A separate report from energy consultant group Wood Mackenzie found enhanced oil recovery, a pioneering extraction method for shale basins, could add between 1.5 million and 3 million barrels per day in oil production by 2030.

In mid-December, when U.S. oil prices were 6.5 percent higher than they are now, EIA said there was still some momentum for U.S. shale oil. While drilling activity is expected to decline, the administration said at the time of the report that oil prices were high enough to support continued drilling development in Eagle Ford and other lucrative shales.