The CEO of U.S. oil giant Chevron Corp. on July 20 said the uncertainty of the COVID-19 pandemic has it planning for "choppy" oil prices and economic activity globally.

Chevron said July 20 it would buy oil and gas producer Noble Energy Inc. for about $5 billion in stock, the first big energy deal since the coronavirus crisis started.

"The crystal ball is cloudy right now," Mike Wirth said in an interview. "There’s so much uncertainty on the trajectory of the pandemic, the rate of development of effective vaccines and government policy interventions to try to manage risk between here and there. It's a fluid environment. We expect choppy economic and price activity."

But Chevron expects long-term demand growth for natural gas from population growth and needs to lower greenhouse gas emissions, Wirth said.

The deal boosts the company's natural gas portfolio with Noble's flagship Leviathan Field in Israel, the largest natural gas field in the eastern Mediterranean.

Noble's holdings also include shale properties in Colorado and in the Permian Basin, the top U.S. shale field, where Noble's 92,000 acres (37,230 hectares)is a "a nice but undersized Permian position" that compliments Chevron's existing land, Wirth said.