HOUSTON, Dec. 1 (Xinhua) -- The number of active drilling rigs in the United States increased to 625 this week, up by three from the previous week but down by 159 from last year, according to the weekly data released Friday by Houston-based oilfield services company Baker Hughes.
These active drilling rigs included 505 oil rigs operating in the U.S. oil fields, up by five from the previous week; 116 gas drilling rigs, down by one from last week; and four miscellaneous rigs, also down by one from last week.
The rigs included 603 land drilling rigs, one inland water rigs, and 21 offshore drilling rigs.
Of them, 54 are directional drilling rigs, 559 are horizontal drilling rigs and 12 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, and an engine of supply growth outside the Organization of the Petroleum Exporting Countries in the past years. ■