Schlumberger (NYSE:SLB), the world's oilfield service leader, experienced what can only be called a difficult day. Not only were its earnings a disappointment and its look at the future less than enthusiastic, but Mr. Market didn't take the news well and stripped $3.40 from Schlumberger's share price following the announcement.

The company reported third-quarter income of $787 million, a 48% slide from the same quarter a year ago, when the company earned $1.53 billion. On a per-share basis, results dipped 4% sequentially, excluding $207 million in charges during the second quarter of this year. Diluted earnings per share were $0.65 per share for the most recent quarter, compared to $1.25 in the third quarter of 2008.

Schlumberger, which serves everyone from big integrated companies like Total (NYSE:TOT) to the world's state-owned oil companies, generated $4.95 billion in revenue through its Oilfield Services segment. That number was down 22% year on year. WesternGeco, its seismic unit, had its top-line shrink 48%, to $463 million, from the comparable quarter last year.

During the quarter, Schlumberger teamed up with National Oilwell Varco (NYSE:NOV) in a joint venture to provide high-speed drill-string telemetry as a safety and efficiency measure in petroleum operations. It also performed work for Devon (NYSE:DVN) in the Barnett Shale, Apache (NYSE:APA) in the North Sea, Anadarko (NYSE:APC) in the Gulf of Mexico's booming deepwater, and Noble Energy (NYSE:NBL) in Equatorial Guinea. Its work for public companies doesn't begin to list the many projects the company undertook for state companies across the globe.

Nevertheless, CEO Andrew Gould was somewhat less than euphoric during the company's call following its earnings release. For instance, as he noted, "In North America, we feel the current slight recovery in drilling to be fragile and not likely to significantly improve service activity and pricing until late 2010." As to natural gas, he noted, "We consider that world gas markets are oversupplied and will remain so for some time, absent a strong recovery in industrial demand."

So what should we make of Schlumberger's results for the quarter? My inclination is to remind Fools that, in my opinion, the company, with its size, scope, and technological advantages, remains the leader of the pack in its sector. So if your investment horizon is relatively lengthy, this might be a good time for a buy order.

Schlumberger has been accorded a full five-star status by Motley Fool CAPS players. Why not head for the company's CAPS page and register your opinion?

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Fool contributor David Lee Smith doesn't own shares in any of the companies mentioned. He does welcome your comments. The Fool has a disclosure policy.