ConocoPhillips' (NYSE: COP) leadoff performance as the first of the big integrated oil companies to release earnings for the March-ended quarter hasn't eroded my notion that there will be few surprises from the group this quarter. I'm expecting the likes of ExxonMobil (NYSE: XOM), Chevron (NYSE: CVX), BP (NYSE: BP), and Royal Dutch Shell (NYSE: RDS-A) (NYSE: RDS-B) to follow suit with increased revenues and earnings from higher oil realizations, probably offsetting very slightly lower production volumes.

That's how it played out at Conoco, which increased its net income to $4.14 billion, or $2.62 for the quarter. That was 17% higher on the net income line than the $3.55 billion, or $1.12 a share, recorded in the March 2007 quarter. And as testimony that some companies are just too complex for to-the-penny modeling by outside observers, the analysts had been looking for about $2.42 on the per-share line.

Conoco's earnings contribution from the upstream (exploration and production) sector was $2.9 billion, up nearly 24% from the first quarter of 2007, when world crude prices were considerably lower. Nevertheless, as is becoming something of the order of the day among the global operators, daily production in barrels of oil equivalent slid 2.7% from the December quarter and 11.4% year over year.

The biggest reasons for the drop from a year ago were Hugo Chavez's expropriation of the company's Venezuelan assets and an exit from Dubai. At the same time, the company's investment in Russian oil company Lukoil yielded $710 million, 177% more than in the year-earlier quarter. It's also a touch surprising that, despite stratospheric crude prices, James Mulva, Conoco's CEO, said the company likely won't increase its capital budget this year, but probably would buy back additional shares.

Predictably, downstream (refining and marketing) results fell by 54% from the year-ago quarter, as crude prices ran far more than the levies on refined products. The company also experienced unplanned downtime at its Gulf of Mexico refineries.

Conoco's shares are up about 20% in the past year, despite crude gas prices far exceeding their year-ago levels. On that basis, and with some experts contending $200 stickers on barrels of oil are not far off, I believe that Fools would be well advised to include significant energy representation in their portfolios. Beyond that, ConocoPhillips might make an excellent name for inclusion on the producers' side.

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Fool contributor David Lee Smith's crudely constructed portfolio doesn't include shares in any of the companies mentioned. He does welcome your questions or comments. The Fool has a disclosure policy.