While some investors have looked upon the recent decline in crude oil prices as a time to exit the energy sector, the largest of the oil services companies, Schlumberger (NYSE:SLB), continues to expand its revenues and income meaningfully, and to project continued solid results.

On Friday, the company reported that its revenues for the fourth quarter of 2006 had increased by 33% to $5.35 billion, from the $4.02 billion it recorded in the final quarter of 2005. At the same time, its income from continuing operations leaped 77% to $1.13 billion year over year, not including charges and credits. This increase led to fully diluted per-share earnings of $0.92 per share, up from $0.52 per share a year earlier (again, before charges and credits).

The company's two operating divisions also weighed in with solid results for the quarter. Schlumberger Oilfield Services provides technology, project management, and data assistance to oil and gas producers like ExxonMobil (NYSE:XOM) and British Petroleum (NYSE:BP), as well as to smaller independent producers. The unit increased its revenues in the quarter to $4.63 billion, 30% higher than those for the comparable 2005 quarter.

Schlumberger's other unit, WesternGeco, provides sophisticated seismic, development, and prospect measurement services to the exploration and production companies. Its own quarterly results included a 55% year-on-year increase in revenues.

In the company's conference call following the release of its quarterly results, Schlumberger CEO Andrew Gould repeated an assessment he had made last September at an investor conference that, assuming the absence of any dramatic global economic slowdown that would reduce hydrocarbon demand, the company "will continue to see high growth through the end of this decade and well into the next." He also repeated another earlier comment that "growth rates would eventually slow from the breakneck pace of 2006, but would remain well above those experienced over the long, slow post-1986 industry adjustment."

Perhaps of even more importance, at least to this Fool, was when Gould noted, "Short-term declines in commodity prices inevitably produce varying activity growth rates if they are sustained long enough. However, maintaining the production base for both oil and natural gas in the face of accelerating decline rates, poorer quality or more difficult reservoirs and eroding reserve replacement ratios will mean than any moderation in activity will be short-lived and self-correcting."

The last quote involves a pair of sentences I wouldn't want to have written, but together they impart a thought that I think is important for Fools assessing the energy services sector today. Indeed, they might be effectively translated to simply state that, with the need to steadily increase the world's crude production in the years ahead, negative energy commodities cycles are unlikely to last long.

Gould's thoughts should, I think, be treated as meaningful by Foolish investors. Indeed, their message, coupled with the results of Schlumberger's quarter, cause me to counsel Fools to carefully examine such energy service companies as -- in addition to Schlumberger -- Baker Hughes (NYSE:BHI), another of the larger, multiservice companies in the group, along with deepwater drillers Transocean (NYSE:RIG) and Diamond Offshore (NYSE:DO) and underwater services provider Oceaneering (NYSE:OII).

For related Foolishness:

The Motley Fool can help you discover winning companies for your portfolio. Whether you're focused on income, high growth, or small-caps -- or some combination of all three -- we're here to help you make money. Free trials are available for all of our newsletter services, and there's never an obligation to buy.

Fool contributor David Lee Smith owns shares of Schlumberger, but does not have positions in any of the other companies mentioned. He welcomes your questions or comments. The Fool has an ironclad disclosure policy.