HOUSTON, Dec. 2 (Xinhua) -- The number of active drilling rigs in the United States stood at 784 this week, unchanged from the previous week and up by 215 from last year, according to the weekly data released Friday by Houston-based oilfield services company Baker Hughes.

These active drilling rigs included 627 oil rigs operating in the U.S. oil fields, 155 gas drilling rigs, and two miscellaneous rigs, all the same as last week.

The rigs included 763 land drilling rigs, three inland water rigs, and 18 offshore drilling rigs.

Of them, 48 are directional drilling rigs, 711 are horizontal drilling rigs and 25 are vertical drilling rigs.

The Permian Basin in western Texas and eastern New Mexico has been the largest source of shale oil production growth in the United States, an engine of supply growth outside the Organization of the Petroleum Exporting Countries in the past years.