HOUSTON, Sept. 27 (Xinhua) -- The number of active drilling rigs in the United States fell by eight to 860 this week, down 194 rigs year-on-year, according to the weekly data released by Baker Hughes on Friday.
According to the Houston-based oilfield services company, these active drilling rigs included 713 oil rigs operating in the U.S. oil fields, down six; 146 gas drilling rigs, down two; and the miscellaneous rig remained at one.
Of the 860 rigs, 835 are land drilling rigs, down seven; 24 offshore drilling rigs, down one; and an inland waters drilling rig remained at one.
Of them, 57 are directional drilling rigs, 752 are horizontal drilling rigs and 51 are vertical drilling rigs. No state reported any increase in drilling rigs, while Texas lost the most with five to 418 rigs.
The number of horizontal drilling rigs this week decreased by four, after a decrease of 20 during the previous week. Horizontal drilling is one of the most renowned technologies in the petroleum industry, which has brought about a revolution in worldwide energy production.
With the combination of hydraulic fracturing and horizontal drilling, oil production has increased significantly, and this is termed as a "Shale Revolution."
According to the U.S. Energy Information Administration (EIA), hydraulically fractured horizontal wells accounted for 69 percent of all oil and natural gas wells and 83 percent of the total linear footage drilled in the country.
By far, the Permian basin has been the largest source of shale oil production growth in the United States, which has become the engine of supply growth outside the Organization of the Petroleum Exporting Countries in the past years.
