HOUSTON, Sept. 23 (Xinhua) -- The number of active drilling rigs in the United States increased to 764 this week, up by one from the previous week and 243 from this time last year, according to the weekly data released Friday by Houston-based oilfield services company Baker Hughes.
These active drilling rigs included 602 oil rigs operating in U.S. oil fields, up by three from the previous week; 160 gas rigs, down by two from last week; and two miscellaneous rigs, the same as last week.
The rigs included 744 land drilling rigs, four inland water drilling rigs, and 16 offshore drilling rigs.
Of them, 46 were directional drilling rigs, 693 were horizontal drilling rigs and 25 were vertical drilling rigs.
So far, the Permian Basin in western Texas and eastern New Mexico has been the largest source of shale oil production growth in the United States, having become an engine of supply growth outside the Organization of the Petroleum Exporting Countries in the past years.