The number of operating drilling rigs in the United States fell by three this week, driven by  a decline in natural gas rigs, the Houston oilfield services company Baker Hughes reported.

Oil drillers added one rig, but that was offset by a decline of four natural gas rigs. All told, 1,059 rigs were operating in U.S. oil and gas fields, up from 933 a year ago.

More than 860 oil rigs were drilling oil, up from 747 last year.

Drillers pulled a net four rigs from Texas oil and gas fields over the week. The drilling fleet in the Permian Basin in West Texas shrank by four rigs. The Eagle Ford shale in South Texas, however, added two rigs.

The Permian still dominates drilling activity with 476 rigs, accounting for more than half the oil drilling rigs in the country. The Eagle Ford is the second most active play, with 82 active rigs.