DOW JONES NEWSWIRES Nabors Industries Ltd.'s (NBR) first-quarter earnings more than doubled on continued strong growth from the company's drilling operations in the continental U.S., helping revenue growth exceed analysts' expectations. The land-drilling oil contractor's continental U.S. drilling unit's adjusted profit jumped 33%, as rig activity grew from a year ago. Nabors joined larger rivals, including market leader Schlumberger Ltd. (SLB), in reporting a stronger first-quarter profit, although results across the industry weren't always as strong as analysts expected. There had been concerns the industry's results would be tempered by severe winter weather and the political crises in the Middle East and North Africa. The first quarter is often the oilfield services sector's least profitable, with fewer product sales and winter weather that can freeze activity in some basins. Nabors posted a profit of $82.8 million, or 28 cents a share, up from $40.2 million, or 14 cents a share, a year earlier. Excluding weather-related delays and other impacts, adjusted earnings grew to 29 cents a share from 21 cents. Revenue surged 57% to $1.41 billion. Analysts surveyed by Thomson Reuters expected a profit of 34 cents a share on revenue of $1.29 billion. Drilling revenue grew 39% in the continental U.S. segment and climbed 7% internationally. Shares closed up 1.2% to $32.06 and were inactive in after-hours trading. The stock is up 37% this year. -By John Kell, Dow Jones Newswires; 212-416-2480; john.kell@dowjones.com