HOUSTON, March 31 (Xinhua) -- The number of active drilling rigs in the United States decreased to 755 this week, down by three from the previous week but up by 82 from this time last year, according to the weekly data released by Houston-based oilfield services company Baker Hughes Friday.
These active drilling rigs included 592 oil rigs operating in U.S. oil fields, down by one from the previous week; 160 gas rigs, down by two from last week; and three miscellaneous rigs, the same as last week.
The rigs included 736 land drilling rigs, one inland water drilling rig, and 18 offshore drilling rigs.
Of them, 51 were directional drilling rigs, 691 were horizontal drilling rigs and 13 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.