Oil giant Chevron Corp. missed estimates for second-quarter profit Friday, hurt by weak refining margins, sending its shares down 1.5% in premarket trading.

The miss came after Chevron warned in June that maintenance work at some its oil and gas production and refining facilities would have an impact on its results.

Earnings from pumping oil and gas were down 9.4% from a year earlier. Profit from producing gasoline and chemicals was also down about 60% to $597 million.

"Despite recent operational downtime and softer margins, we remain poised to deliver significant long-term earnings and cash flow growth," CEO Mike Wirth said.

The company, whose $53 billion takeover of Hess has been delayed to at least May next year, reported adjusted earnings of $2.55 per share, missing analysts' estimates of $2.93.