HOUSTON, Sept. 22 (Xinhua) -- The number of active drilling rigs in the United States decreased to 630 this week, down by 11 from the previous week and by 134 from one year ago, according to the weekly data released Friday by Houston-based oilfield services company Baker Hughes.
These active drilling rigs included 507 oil rigs operating in the U.S. oil fields, down by eight from the previous week; 118 gas drilling rigs, down by three from last week; and five miscellaneous rigs, unchanged from last week.
The rigs included 608 land drilling rigs, three inland water rigs, and 19 offshore drilling rigs.
Of them, 56 are directional drilling rigs, 558 are horizontal drilling rigs and 16 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.