It's unlikely that they do it purposefully, but it's nevertheless intriguing to note that Halliburton (NYSE: HAL), the second-largest member of the oil-field-services sector, and Schlumberger (NYSE: SLB), its larger rival, appear to be taking turns leading off their sector's earnings reports.

First up for services
This time it was Halliburton's turn, with its Wednesday report, while Schlumberger will take center stage on Friday. In Halliburton's case, results were surprisingly solid. Its net income reached $627 million, or $0.68 per share, compared to a first-quarter 2011 figure $511 million, or $0.56 a share -- a nearly 23% year-over-year improvement on the net income line. Revenue climbed by 30% to $6.87 billion.

Excluding special items, the company earned $0.88 per share. Analysts who follow Halliburton had anticipated per-share earnings of $0.85 on revenue of $6.79 billion. So chalk that up as the service sector's first beat of the new earnings season.

The company's results included a $300 million charge related to its role in the 2010 disaster in the Gulf of Mexico involving BP's (NYSE: BP) Macondo well. That disaster included an explosion aboard Transocean's (NYSE: RIG) Deepwater Horizon rig, the deaths of 11 workers, and a massive spill that gushed oil into the Gulf until it was brought under control in mid-summer of 2010. BP is likely to pay about $37 billion for its part in the tragedy. And while Halliburton, which was responsible for the cementing of the well, and BP continue to quibble over the service company's ultimate financial responsibility for the event, the quarter's charge related to "probable losses" likely stems from eventual settlements.

Oilier by the minute
A significant shift in North American oil-field activity during the quarter ended up benefiting Halliburton. With crude prices remaining at high levels and natural gas in the doldrums, exploration and production companies increased their efforts to search for and produce oil. As such, the number of rigs operating in oil fields expanded by 12%, while those drilling for natural gas slid by 17%. Oil operations tend to be more service-intensive than those producing dry gas.

Partially as a result of that structural change, Halliburton's North American revenue increased by 40%, while its operating income on the continent expanded by 45%. Those figures compared to revenue growth of 27% and an operating income leap of 67% in Latin America. At the same time, the company's other two operating regions, Europe/Africa/CIS and Middle East/Asia contributed year-over-year operating income gains of 76% and 44%, respectively.

As The Wall Street Journal noted, almost tongue-in-cheek, Halliburton -- along with its peers -- is digging deeper into its pockets to handle the skyrocketing cost of guar, a legume that's used as a thickening agent in toothpaste, bagels, and dynamite. Not that the big services company produces any of those items, but guar also is used to thicken fracking fluids. According to Halliburton CEO Dave Lesar, "The problem with guar is it's probably the fastest-moving commodity price that I've ever seen."

Fracking's future
Looking ahead, Lesar is somewhat cautious about the future effects of the U.S. oil and gas industry's increasing work in liquids-prone venues. "As we renew contracts and win new work, we expect to see frack pricing become more challenging, but the impact will vary by basin. The dry natural gas basins will be the most challenged, followed by those more easily accessible oily basins ... such as the Eagle Ford."

Nevertheless, Lesar is clearly satisfied with his company's position in its industry:

[We] continue to expand our capabilities and drive efficiency through technology and redesign of our operations. We have just rolled out our first series of Q10 pumps, which we believe are the most efficient and lowest-maintenance pumps in the industry. We are also deploying a smartphone technology to automate many of the tasks that are now performed manually in the industry today.

It's also noteworthy that Lesar is hardly down in the dumps about what he sees in the Gulf of Mexico. As he said, "We remain optimistic about the recovery of activity and believe that margins will continue to increase as our customers adapt to new regulations and industry efficiency improves."

The Foolish bottom line
Especially given Halliburton's strong leadoff, we can now look with anticipation to the results generated by Schlumberger and Baker Hughes (NYSE: BHI), the sector's third-largest player, which will report its results next week. In March, Baker cautioned that its first-quarter profits could decline, as it too will likely be gored by guar prices. Nevertheless, I continue to urge Fools to keep close tabs on the service companies, perhaps beginning by adding a clearly solid Halliburton to your individual watchlists.