At first glance it appears that the final two days of last week brought us something of a "twofer" in the form of the remaining U.S.-based members of big oil -- now that ConocoPhillips (COP -0.43%) has reconstituted itself in an independent producer -- ExxonMobil (XOM 0.02%) and Chevron (CVX 0.44%). Indeed, with the global economy continuing to slow and other factors weighing in, both big companies saw their earnings decline from those of the third quarter of 2011.

But in the final analysis, the factors that affected the two companies' results were quite different, one from the other. Without reiterating Exxon's quarterly details, you'll likely recall that the bigger company took a significant year-on-year hit in the contribution from its upstream operations, but regained a bit of that decline downstream. Chevron, however, turned in results that were lower across the board, especially downstream.

A less that attractive miss
Overall, Chevron's net income slid to $5.25 billion, or $2.69 per share, compared with $7.83 billion, or $3.92 a share a year earlier. However, if you back out one-time items from the reported results, the company earned $2.55 per share, a substantial shortfall from the $2.83 per share consensus among the analysts who follow the California-based company. Total revenues for the quarter were down 10% year-on-year to $58.04 billion.

Looking first at the company's exploration and production operations, net oil-equivalent production declined to 2.52 million barrels per day, from 2.60 million daily barrels in the comparable quarter a year earlier. All was not negative in the sector, however. Production actually increased in such locations as Thailand, Nigeria, and the United States. But those increases were more than offset by planned maintenance, normal field declines, the continued shut-in of the Frade Field offshore Brazil. There also was a temporary reduction of production in the Gulf of Mexico, as Hurricane Isaac made its way across that body of water.

In addition to reduced volumes, average price realizations were down for both liquids and natural gas. In the U.S., for instance, the former slid to $91 per barrel, from the year-ago average of $97, while natural gas fell more than 36% to $2.63 per thousand cubic feet, from $4.14 for last year's third quarter.

Sliding downstream
Downstream, while earnings from U.S. operations were down 35% year-on-year, in large part as a result of a major early August fire in the company's Richmond, Calif., refinery. Internationally, the segment's contribution to earnings was down fully 82% from a year ago. However, results for the 2011 period included a gain of about $500 million from the sale of the Pembroke Refinery and related assets in the U.K. and Ireland.

But lest you get the impression that all is askew with the big company, it's worth noting that, as CEO John Watson said at release time, the massive Gorgon LNG project -- for which Chevron serves as operator in a partnership that includes ExxonMobil and Royal Dutch Shell (RDS.B) -- is now at least half complete. The same can been said of the Bigfoot and Jack/St. Malo projects in the deepwater Gulf of Mexico.

An expanding deepwater market
At the same time, as the quarter came to an end, the company was awarded participation in a pair of deepwater blocks offshore Sierra Leone in West Africa. Chevron already enjoys a strong presence in this important producing area, where its new blocks cover about 2,100 square miles, with water depths that range from 4,900 to 9,800 feet.

Even more recently, the company achieved another natural gas discovery offshore Western Australia, where, with the aforementioned Gorgon project, it already is the proverbial star of the gas discovery show. The latest discovery is, in fact, located in the Carnarvon Basin, in the greater Gorgon Area. As is the case with Gorgon, Chevron holds a 50% interest in the latest discovery, with Exxon and Shell dividing the remainder equally.

In addition, Chevron acquired 246,000 net acres in the revitalized Permian Basin from Chesapeake Energy (CHKA.Q). The new addition brings to about 1.5 million its acres in the liquids-prone venue. As CFO Patricia Yarrington observed on the company's call: "The new acreage strategically complements our existing operation and provides us with additional growth potential in the Permian."

The Foolish bottom line
I could continue to describe other successes at the company. But as many energy-investing Fools already recognize, I consider the company to be soundly managed and the possessor of a host of attractive worldwide assets. The earnings pullback in the most recent quarter clearly were attributable to temporary phenomena or to circumstances beyond the company's control. On that basis, I'd be an active buyer of Chevron shares on any sort of pullback and would ascertain that the company is included on My Watchlist.