Schlumberger Ltd , the world's largest oilfield services company, posted a higher-than-expected profit boosted by strong demand in North America, and said it expected brisk activity to continue.

Like others in the oilfield service sector, Schlumberger depends on spending by its oil and gas-producing customers, and the rising oil price has bolstered confidence that its business will benefit in 2011.

It was a strong quarter, better than expected, said Bill Herbert, analyst with Simmons & Co International, a boutique investment firm in Houston.

But as important as the results was the encouraging outlook that Mr. (Andrew) Gould put forth, he added, referring to Schlumberger's CEO and chairman.

The company's shares gained 2.6 percent to $87.49 in premarket trading.

Schlumberger's global reach gives it a broad perspective on the international oil and gas business, and market watchers look to the company to set the tone for the industry.

The consensus forecast for demand in 2011 shows a further healthy increase, Gould said in a release.

Oil prices have moved into a range that will encourage increased investment, particularly in exploration, which remains the swing factor in operators' budgets.

A closely watched survey of energy companies released by Barclays in December showed that spending on global exploration and production is expected to jump 11 percent this year, with much of that spending to occur in emerging markets.

Steady drilling for natural gas in the North America has begun to decline because of weak prices for the fuel, and though producers have shifted to oil and other liquids projects, growth in the continent is expected to flatten later in 2010.

North America has been the bright spot of 2010, but we'll see that slow down this year eventually, said Brian Youngberg, analyst with Edward Jones.

Still, with demand for oilfield services outside North America growing and expectations that oil prices will remain strong, the company's future looks bright.

We think they could see 30 percent earnings growth this year, and potentially, it could be comparable to that in 2012, he added.

Fourth-quarter profit rose to $1.04 billion, or 76 cents per share, from $817 million, or 67 cents per share, a year earlier.

Excluding one-time items, Schlumberger earned 85 cents per share, topping the 77 cents that analysts on average had forecast, according to Thomson Reuters I/B/E/S.

Revenue rose 58 percent to $9.07 billion, while analysts were expecting $8.7 billion.

Schlumberger closed the $11 billion takeover of Smith International in August, which gave it complete control of drilling fluids business M-I Swaco.

Revenue from oilfield services climbed 16 percent, while revenue at seismic mapping division WesternGeco rose 2 percent.

Schlumberger shares have risen by 23 percent in the past year, roughly in line with the Philadelphia Stock Exchange oil service index <.OSX> but more than the 17 percent gain for rival Halliburton Co , which is expected to report earnings on Monday.

(Additional reporting by Braden Reddall in San Francisco; Editing by Lisa Von Ahn, Derek Caney, Steve Orlofsky, Dave Zimmerman)