U.S. energy company executives polled by the Federal Reserve Bank of Dallas have an optimistic outlook driven by upticks in activity and a jump in oil prices, according to a survey released on June 23.

Oil and gas producers are spending more money on projects and expect to raise that amount again next year, according to executives contacted by the Dallas Fed.

The rosier outlook comes as oil prices on June 23 climbed to the highest levels since late 2018 on crude inventory declines, while shares in oil and gas companies traded higher.

The Dallas Fed survey includes executives from Texas, Louisiana and New Mexico.

Three-quarters of executives said they believe there will be a global crude oil supply gap in the next two to four years.

A lack of capital is constraining the U.S. industry from adding much to supply, survey respondents said.

Of 400 institutional investors that one executive knows, “approximately one is willing to give new capital to oil and gas investment,” said one anonymous survey respondent. “This underinvestment coupled with steep shale declines will cause prices to rocket in the next two to three years.”

While the U.S. industry has a reputation for rushing equipment back to the field as prices rise, OPEC and allies, known as OPEC+, meets July 1 to discuss further easing oil output cuts.

“Don’t take the bait, drillers: Stay capital disciplined and enjoy the higher prices for your product,” another U.S. executive said.

Oilfield services firms reported improvement in equipment use, operating margins and the prices received for services.

Most executives—82%—do not think a carbon tax should be used to reduce carbon emissions, according to the survey.