There are a couple of ways to view the oilfield services industry. On the one hand, the sector can be grouped according to specific functions, beginning with the Big Three -- Schlumberger (NYSE:SLB), Halliburton (NYSE:HAL), and Baker Hughes (NYSE:BHI) -- and then listing such other sub-sectors as the drillers, transportation companies, equipment manufacturers, etc. Or you can just as easily categorize the space as Schlumberger -- and all the rest.

I prefer the latter approach, because I know of few other industries as dominated by one sparkling, way-out-front leader. This is the case with those firms that help the big and small exploration and production (E&P) companies -- from ExxonMobil (NYSE:XOM), Chevron (NYSE:CVX), Petrobras (NYSE:PBR), and Chesapeake (NYSE:CHK), as well as the tiniest independent -- locate and produce oil and natural gas. On Friday, almost as if the rest of the industry is acceding to its unofficial leadership, Schlumberger will be an early entrant in the parade of energy companies telling us about their September earnings results.

Global presence
The Schlumberger of today is a massive company, with a market value of more than $130 billion and in excess of $21 billion in annual revenues. Its 70,000 employees include 140 nationalities and operate in about 80 countries, with its principal offices located in Houston, Paris, and The Hague.

Today, the company maintains two operating units -- Schlumberger Oilfield Services and WesternGeco. The larger Oilfield Services unit provides a host of solutions and services to E&P companies once the likelihood of a productive oil or gas reservoir has been determined, and later, when production begins to wane and the need for stimulation is indicated.

As in the company's earliest days, its solutions comprise various forms of logging and drilling services. These include preserving the well's structure by cementing it with a special oilfield cement that sets up more slowly than the verities used in your home's foundation or on the nation's highways. Still other services in Oilfield Services' technically sophisticated bag of tricks include coiled tubing well stimulation, along with other forms of inducing more production from tired wells, and sand control. The company also provides its customers with an array of well testing and completion services, and offers a full line of consulting and project management support.

The smaller of the two units, WesternGeco accounts for just over 10% of Schlumberger's revenues, but is no less important to the company's customers. It provides a range of seismic assistance and services to E&P companies in the early stages of attempting to locate potentially productive oil and gas reservoirs.

The importance of research
Schlumberger is also noteworthy for the scope of the research and development expenditures, which are intended to maintain its recognized technological leadership. Last year, for instance, the company invested $619 in R&D -- more than the rest of the industry combined -- as it supported 23 research and engineering facilities around the world.

And Fools, if you're attempting to get up to speed on the energy industry and its various parts, I have a couple of tips. First, in announcing his company's earnings, Schlumberger CEO Andrew Gould almost certainly will make more informative comments about global energy conditions than will all the other industry CEOs combined. And beyond that, the company's website is a font of information and instruction about energy. For instance, the site contains a glossary of oilfield terms that is so comprehensive it includes 521 entries beginning just with the letter "s."

Big profits
If you'd bought Schlumberger shares a year ago and held them, you'd have about an 85% profit today. Clearly, the company has benefited from a number of factors, including its respected technological leadership, its worldwide operating scope, and the unabated upward march of oil prices during 2007. The fact that its earnings have grown steadily (they were up over 40% year over year in the June quarter) also hasn't hurt.

When September results are released on Friday, it's expected that Schlumberger's per-share earnings will have grown about 30% from the prior year, so the company is still showing impressive growth. But, Fools, even if you never buy a single share of Schlumberger stock, I suggest that you follow the company closely and get to know it well. Your energy IQ will thank you.

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This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.