We've jumped smack-dab into the quarterly circus known as earnings season. In our current active political climate, the energy companies might incite more than the normal amount of carping about the size of their latest profits. But increasing profitability is simply part of crude oil's steady march into the $90-a-barrel range.

The past couple of quarters have seen an interesting dance among the integrated companies. First, downstream profits led the parade early in the year, but with refinery margins shrinking in the face of crude prices' rise, upstream carried the day in the September-ended period. It now appears that the sector's results -- kicked off next week by Schlumberger (NYSE: SLB) -- will look ever rosier for producers.

Since the sector was the hottest overall group in 2007, its ability to continue to reward shareholders this year should vary from company to company. Nevertheless, it appears that the integrated producers -- including ExxonMobil (NYSE: XOM), Chevron (NYSE: CVX), and ConocoPhillips (NYSE: COP) -- will check in with double-digit year-over-year earnings growth. The primary driver there, of course, will be the big jump in crude prices from last year.

On the services side, earnings growth also should be solid. Schlumberger, for instance, is expected to improve profits by slightly more than 20%, while expectations for Baker Hughes (NYSE: BHI) are only slightly lower. At the same time, offshore drilling leader Transocean (NYSE: RIG), is poised to clock in with stellar growth, both for the quarter and year ahead.

But assuming that they materialize, these gains just might unleash a whole lot of political invective. In any event, however loud the shackle-the-oil-companies cacophony becomes, Foolish investors would be well advised to keep a close eye on this increasingly important and profitable sector.

A deep well of further Foolishness:

Fool contributor David Lee Smith doesn't own a gas-guzzler, not does he possess shares in any of the companies mentioned. He welcomes your questions or comments. The Motley Fool has a fossil-fuel-free disclosure policy.