The Big Oil gang has started to report earnings, with ExxonMobil (NYSE:XOM), Chevron (NYSE:CVX), and ConocoPhillips (NYSE:COP) reporting last week. At first glance, it's somewhat surprising that Chevron managed to eke out a gain, while Exxon's results slid year over year on lower crude prices. But if you back out one-time items, Chevron also suffered a slippage.

Let's take a look at the different companies' respective results and try to find some good news that might benefit us in the year ahead.

The biggest goes first
In spite of Exxon's fourth-quarter dip in earnings, full-year earnings were an all-time corporate record of $45.2 billion. That's up 11% from the prior record of $40.6 billion in 2007.

During the quarter, net income fell to $7.8 billion, or $1.55 a share, versus $11.7 billion, or $2.13 a share a year earlier. With crude prices sliding by about 60% from September through December, the upstream contribution to the company's total fell $2.6 million to $5.6 million. At the same time, its oil-equivalent production dropped by 3% in the quarter, never a good sign for an exploration and production company.

The downstream (refining and marketing) sector did better, with stronger margins leading to about a 6% earnings improvement. The gain occurred despite a loss for the sector in the U.S. of $20 million.

Exxon's capital and exploration expenditures grew by 11% to $6.8 billion during the quarter. At the same time, the company bought back another 119 million shares of its common stock, spending $8.8 billion in the process.

Finally, Exxon has announced that it will spend in excess of $1 billion in three big refineries in the U.S. and Europe, raising its production of diesel fuel by six million gallons per day.

Chevron's special items benefits
And then there was Chevron. The company's net income improved to $4.90 billion, or $2.44 per share. That's up from up from $4.88 billion, or $2.32 a share in the fourth quarter of 2007. However, the most recent quarter included a $600 million gain on an asset exchange transaction, along with $478 million in currency exchange. Without those items, the consensus expectation was $1.82 a share, far lower than a year ago.

In the exploration and production segment, Chevron generated $3.2 billion, a decline of $1.7 billion from the comparable quarter of 2007. But downstream, in light of the expanding margins mentioned above, Chevron earned $2.1 billion, more than a ten-fold increase from the final quarter of 2007.

Unfortunately, however, Chevron's oil-equivalent production was 619,000 barrels a day, down 111,000 daily barrels from the year-ago quarter. Nevertheless, there was a reason for the drop: About three-quarters of the total was related to the September hurricanes in the Gulf of Mexico.

ConocoPhillips, as expected
Friday's Exxon and Chevron results followed the earlier release of results from ConocoPhillips, which, as I earlier had forecast to my Foolish friends, included $34 billion in asset writedowns, as plummeting crude prices took their toll on the values of several of the company's prior-years' acquisitions. Included was a $25.4 billion trimming, primarily relating to the value of the company's 2006 purchase of Burlington Resources, and a $7.4 billion writedown of the company 20% stake in Russia's giant oil company, Lukoil (OTC BB: LUKOY).

Without all these one-time items, Conoco would have checked in with earnings of $1.9 billion, or $1.28 a share.

What's ahead for the sector?
So, on a purely operating basis, the world clearly has become tough on the producers, as compared, for instance, to the bigger oilfield service companies Schlumberger (NYSE:SLB), Weatherford (NYSE:WFT), and Halliburton (NYSE:HAL), all of which reported respectable results. Given the structure of the energy industry, however, those companies all will take longer to reflect lower oil and gas prices than have their producer customers.

Most of 2009 will perpetuate hard times for the producer and service contingents alike. Nevertheless, abandoning the sector completely would be foolhardy. Indeed, commodity price turnarounds could occur as quickly as did the beginning of the skids in July. As a result, I'm still most interested in ExxonMobil, the biggest of Big Oil and an ideal proxy for the overall industry.

ExxonMobil has been rated a four-star company by Motley Fool's CAPS players. Why not weigh in with your thumb pointed either up or down?

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Fool contributor David Lee Smith doesn't own shares in any of the companies mentioned. He does welcome your questions or comments. The Motley Fool has a well-oiled disclosure policy.