Crude oil prices will continue to climb as demand rebounds and supplies remain tight, the head of one of the largest U.S. shale producers said on Aug. 3.

Prices will remain at $100/bbl or more over the next five years, Pioneer Natural Resources CEO Scott Sheffield told investors on a conference call. Pioneer will remain focused in the near term on achieving roughly a 5% production volume growth rate, he added.

“I’m still very optimistic that the oil price is going to continue to march forward, with probably more upside than downside,” Sheffield said.

International Brent futures were trading at about $99/bbl and WTI oil futures in the U.S. were at about $92/bbl on Aug. 3 amid an unexpected 4.5 million-barrel surge last week in U.S. stocks.

OPEC+ members are set to increase oil output by a tiny 100,000 bbl/d from September—the equivalent of 86 seconds of global demand. The small increase has been seen as an insult to U.S. President Joe Biden, who recently went to Saudi Arabia to persuade the producing group to pump more oil to quell high energy prices.

“It was miniscule. They just don’t have the supply,” Sheffield said, pointing to OPEC heavyweights Saudi Arabia and United Arab Emirates.