Number of active U.S. drilling rigs unchanged this week

HOUSTON, Dec. 20 (Xinhua) -- The number of active drilling rigs in the United States stands at 589 this week, unchanged from last week but down 31 from a year ago, according to the weekly data released Friday by the Houston-based oilfield services company Baker Hughes.

These active drilling rigs include 483 oil rigs operating in U.S. oil fields, up by one from last week; 102 gas drilling rigs, down by one from l