Each earnings season, we look forward to poring over quarterly results from the two largest oil-field-service companies–Schlumberger (NYSE: SLB) and Halliburton (NYSE: HAL).

These industry giants’ earnings calls–particularly the wide-ranging discussions hosted by Schlumberger, the world’s largest oil-field services company–provide invaluable insights into other aspects of the energy patch.

Because of Halliburton’s strong presence in the US and Canada, its management team tends to take a more bullish view on the North American market than Schlumberger, which usually emphasizes international activity. Evaluating both companies’ results and commentary helps investors to form a complete picture of key energy markets.

The read-through from Schlumberger and the other major oil-field services companies’ earnings reports and subsequent conference calls are particularly useful because they occur before many other energy-related names announce quarterly results.