Halliburton (NYSE: HAL), the second-largest of the oilfield services companies -- to Schlumberger (NYSE: SLB) -- led off the earnings parade for its group on Monday. And while the company's overall results slid during the most recent quarter, there are clearly reasons for optimism about what lies ahead.

For the quarter, the company earned $206 million, or $0.23 a share, versus year-ago figures of $378 million, or $0.42 per share in the first quarter of 2009. But if you back out special charges involving the devaluation of Venezuela's currency, the company would have earned $0.28 a share, beating both the $0.25 per share consensus expectation and the $0.27 earned per share for the final quarter of 2009.

Looking at Halliburton's two operating segments, the Completion and Production group recorded a $146 million increase in sequential revenues. The strengthening was largely attributable to a solid North American market. However, most other horizons were challenging. The Drilling and Evaluation segment recorded a $71 million sequential decrease in revenue and was similarly concentrated in North America vis-a-vis improved operating income.   

In discussing North American strength during the company's call, CEO David Lesar noted that, "Now these increases varied widely across product service lines and basins, and were most evident in those service intensive plays like the Bakken, Haynesville, Eagle Ford and Woodford, where demand for completion equipment has far outstripped capacity."

But despite the strength in North America, Mr. Lesar provided a cautionary note regarding natural gas fundamentals, which "are causing concern, coming out of the heating season which may disrupt the current rebound in drilling activity." He sees continued downward price pressure on natural gas "for several quarters," but expects unconventional drilling to continue as operators have to drill to keep leasehold.

Despite a "more challenging than expected" environment, Mr. Lesar also expressed optimism for a steady recovery in the international sector during the second half of this year and into 2011.

Halliburton, which is spending $240 million to buy Boots & Coots (AMEX: WEL), the pressure- and fire-control company, is continuing a general consolidation trend in the services sector. For instance, Schlumberger is purchasing Smith International (NYSE: SII), while Baker Hughes (NYSE: BHI) is acquiring BJ Services (NYSE: BJS).

For my money, we're only seeing the beginning of an expanding string of marriages in the services sector. In Halliburton's case, Timothy Probert, the president of global business lines & corporate development, noted that the acquisition will result in a merger of his company's well intervention services into a new product line with Boots & Coots' assets.

I'm convinced that we're in the early stages of a strengthening services sector, and that Halliburton is very much a part of that trend. So I'd urge Fools to remain carefully focused on this solid company.

Fool contributor David Lee Smith doesn't own shares in any of the companies listed above. He'll flip you a nickel, however, for a question or a comment. The Fool has a disclosure policy.