UPDATE 1-Smith Int'l second-quarter profit rises 20 pct

(Adds details, estimates)

HOUSTON, July 24 (Reuters) - Smith International Inc (SII.N: Quote, Profile, Research, Stock Buzz) on Thursday said quarterly earnings rose 20 percent, topping analyst expectations, as high energy prices prompted the oilfield service company's customers to spend more on exploration.

Smith said second-quarter profit was $183.3 million, or 91 cents per share, compared with $153.1 million, or 76 cents per share, a year ago.

Revenue was $2.49 billion, an increase of 18 percent.

Analysts on average expected the Houston company to earn 88 cents per share on revenue of $2.38 billion, according to Reuters Estimates.

Looking ahead, Smith Chief Executive Doug Rock said he was encouraged by the improving market conditions for the second half of the year. (Reporting by Anna Driver; Editing by Steve Orlofsky)