* 2nd-qtr revenue up 29 pct
* Confident about growing N. America margins- CEO
* Shares up 2.5 pct premarket (Adds details, comments; updates shares)
July 24 (Reuters) - Halliburton Co swung to a quarterly profit and handily beat analysts' expectations on higher demand in North America, sending the world's No.3 oilfield services provider's shares up 2.5 percent.
The company's revenue from North America surged 83 percent to $2.77 billion in the second quarter, due to increased demand for pumping and well-construction services in the region.
Halliburton said margins in its biggest market by sales grew "into double digits" in the quarter and CEO Jeff Miller expected margins from the region to improve.
The commentary on margins is crucial as Wall Street was already expecting oilfield services companies to beat last year's weak results.
Last week, bigger rival Schlumberger Ltd also reported strong quarterly results and said it would redeploy all of its pressure pumping fleet by early next quarter.
U.S. oil producers added 94 rigs in the three months to June 30 as shale companies have been able to profitably pump oil even as crude prices hover below $50.
Net profit attributable to Halliburton was $28 million, or 3 cents per share, in the second quarter ended June 30, compared with a loss of $3.21 billion, or $3.73 per share, a year earlier.
The year-ago quarter included a $3.5 billion charge related to the termination of the Baker Hughes deal.
Halliburton's revenue rose 29 percent to $4.96 billion, marking the company's second straight quarter of increase, after seven quarters of double-digit percentage declines.
Excluding items, the company earned 27 cents per share in the reported quarter, while analysts expected a profit of 18 cents, according to Thomson Reuters I/B/E/S.
Halliburton's shares were up at $45.50 in premarket trading on Monday. (Reporting by Nivedita Bhattacharjee and Yashaswini Swamynathan in Bengaluru; Editing by Arun Koyyur)