Weatherford International (NYSE: WFT) on Tuesday followed Halliburton (NYSE: HAL) as the second of the larger oilfield service companies to report its results for the second quarter.

For the quarter, Swiss-based Weatherford reported a net loss of $26.6 million, or $0.04 per share, versus net income of $42 million, or $0.06 per share, for the same quarter a year ago. The company's quarterly revenue increased by 22% to $2.44 billion.

The current year's metrics included costs from the purchase of TNK-BP, the third-largest Russian oil company, which consisted of a joint venture between Britain's BP (NYSE: BP) and a partnership consisting of three Russian billionaires. The all-stock deal, which was announced last year, and was valued at $450 million, resulted in a special non-cash charge of $82 million in the second quarter. There were also $24 million in costs related to severance and investigations.

Without those charges, the company determined that it would have earned $0.11 per share in the quarter, versus a consensus expectation of $0.07 per share among analysts.

On a geographic basis, North America was the star of the show. U.S. revenues increased by 61% to $921 million compared with a year ago. At the same time, revenues grew by 3% versus the first quarter. According to CEO Bernard J. Duroc-Danner, "The outlook for North America appears constructive. Client feedback (also) leads us to believe that operators are planning to accelerate activity in international markets."

In the Middle East/North Africa and Asia, revenues expanded by a single percentage point -- which I'd label as flat -- while Europe/West Africa and the former Soviet Union improved by 39%, largely as a result of the TNK-BP acquisition. Latin America's revenues slid by 12% year over year, primarily because of reduced activity in Mexico.

Looking at the second half of the year, Chief Financial Officer Andy Becnel noted on his company's call that Canadian operations are expected to benefit from cost reductions. And in the U.S., unconventional gas- (and) oil-directed drilling "continue to pull strong growth." At the same time, he mentioned improved activity in countries such as Russia, Iraq, and China, in the Eastern Hemisphere, and Brazil and Colombia in Latin America.

Still waiting in the wings to report are the likes of Schlumberger (NYSE: SLB), Cameron (NYSE: CAM), and Baker Hughes (NYSE: BHI). Until the lineup is complete, however, I'd study the sector carefully, but limit portfolio additions to the two biggest players: Schlumberger and Halliburton.