HOUSTON, Aug. 19 (Xinhua) -- The number of active drilling rigs in the United States fell to 762 this week, down by one from the previous week but up by 259 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 601 oil rigs operating in U.S. oil fields, unchanged from the previous week; 159 gas drilling rigs, down by one from last week; and two miscellaneous rigs, the same as last week.
The rigs included 741 land drilling rigs, three inland water drilling rigs, and 18 offshore drilling rigs.
Of them, 39 were directional drilling rigs, 694 were horizontal drilling rigs and 29 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.