Chemical maker and refiner LyondellBasell Industries reported quarterly profit that beat expectations on Friday as cheap North American shale natural gas helped offset lower margins from expensive crude oil.

The results sent the company's shares up 8% to $44.13 in midday trading.

The company expects cheap natural gas to continue to boost results, and said despite economic volatility it would continue to invest in North American operations that use the natural gas.

"While we expect global economic uncertainty to continue and related volatility to limit our near-term visibility, we remain focused on the fundamentals," Chief Executive Officer Jim Gallogly said.

For the second quarter, net income fell to $768 million, or $1.33 per share, from $803 million, or $1.38 per share, a year earlier.

Excluding one-time items, the company earned $1.66 per share. By that measure, analysts, on average, expected $1.41, according to Thomson Reuters I/B/E/S.

Revenue fell 16% to $11.25 billion. Analysts expected $13 billion.

Operating income grew 38% at the North American olefins unit, which uses shale natural gas to make ethylene.

In contrast, operating income was flat at the European olefins unit, which primarily uses crude oil-derived naphtha to make ethylene. Ethylene is a key chemical used to make plastics and many other consumer goods.

LyondellBasell said it expected a strong performance at its North American unit for the rest of the year, given access to shale natural gas, and for its European operations to lag.

"The situation has been, and continues to be, favorable for U.S. producers," Gallogly said. "We believe that it will stay this way for the foreseeable future, although we will likely see pockets of volatility."

The company, which is technically based in the Netherlands but run out of Houston, boosted its dividend by 60% in May, saying recent debt payments have freed up cash that can be returned to shareholders.

LyondellBasell's debt now stands at $4.31 billion, with $2 billion in cash on hand.