Schlumberger , the world's largest oilfield services company, reported a decline in first-quarter earnings on Friday as the global slump in energy demand forced its customers to reduce activity and seek price reductions.

Net profit fell to $938 million, or 78 cents per share, from $1.3 billion, or $1.06 per share, a year earlier.

Analysts on average had expected earnings per share of 73 cents, according to Reuters Estimates.

Halliburton Co and Weatherford International Ltd reported drops in first-quarter profits earlier this week.

Shares of Schlumberger, down 58 percent from a high of $111.91 last July, are up 10 percent so far in 2009.

(Reporting by Matt Daily in New York and Braden Reddall in San Francisco; Editing by Lisa Von Ahn)