HOUSTON, Dec. 22 (Xinhua) -- The number of active drilling rigs in the United States decreased to 620 this week, down by three from the previous week and by 159 from last year, according to the weekly data released by Houston-based oilfield services company Baker Hughes on Friday.
These active drilling rigs included 498 oil rigs operating in U.S. oil fields, down by three from the previous week; 120 gas rigs, up by one; and two miscellaneous rigs, down by one.
