After two decades of depressed global oil and gas exploration, Frontier exploration is back. The industry’s largest producers are cutting spending on costly global efforts as they lean toward West Texas’ Permian Basin and other parts of the US onshore, as well as proven offshore basins, including the Gulf of Mexico.

For context, that decision proved wise: The shale boom — with horizontal drilling combined with hydraulic fracturing, or fracking — turned the US from a country pumping 5 million barrels of oil a day 20 years ago to a world-leading powerhouse that produces nearly 14 million barrels per day and even exports nearly 5 million barrels.

That allows Chevron, Exxon Mobiletc. to ease the metaphorical gas pedal around the world and focus more on literal oil and natural gas drilling within. With US shale now potentially up and up—or even entering a slight decline—the pendulum is swinging again.

Global exploration is recovering from historically low levels, so growth remains slow, but it’s clearly rebounding, said Patrick Rutty, director of global intelligence at Enverus.

“Due to recent drilling success and reduced concerns about peak (oil) demand, the industry is reprioritizing exploration, a dynamic that should lead to resource extraction at relatively high levels over the next five years,” said Rutty. He added that there remains a risk of a global oil shortage later this decade as demand continues to rise in the short term.

Another reason why global exploration has stalled is the ongoing projection that global oil demand will eventually peak and begin to decline later this century as the world transitions to electric cars and other cleaner fuel sources. But, while demand growth has slowed, it has continued to rise, and a deficit now looks like a bigger risk in the short term.

That’s especially true because US shale wells dry up much more quickly than conventional wells after producing large volumes of oil for a few years.

Back to the borders

So Big Oil is now on the move.

A landmark: Former war-torn Libya has granted exploration licenses to international companies for the first time in nearly 20 years. More on Chevron, Italy Eniin Spain Repsoland some won new licenses.

Chevron returned to Libya after first exiting the country in 2010, during a period of severe political unrest.

“Libya has significant proven oil reserves and a long history of producing its resources,” said Chevron vice president of exploration Kevin McLachlan. “Chevron is confident that its proven track record in developing oil and gas projects and its technical expertise give it the ability to support Libya to further develop its resources.”

Chevron said the deal reflects the company’s growing focus on the Eastern Mediterranean region of North Africa and the Middle East. Chevron is also in the process of expanding its operations in Egypt, Cyprus, and Turkey.

In its call on February 10, BP called his offshore drilling effort in Libya is “the most closely guarded exploration well in the industry today.”

Chevron is also negotiating a potential return to Iraq. In October, Exxon Mobil signed an agreement to return to Iraq as well.

Chevron chairman and CEO Michael Wirth highlighted the global exploration momentum in his Jan. 30 earnings call. He said that there is a wider increase in interest from countries that want American companies to invest in their resource extraction.

“It’s been a decade or more since we last had any kind of serious look at Libya. Those things are changing,” Wirth said. “The resource potential of some of these countries is undeniable. Iraq and Libya are two of the largest resource holders in the world.”

Chevron’s main oil production center is, currently, the United States—which accounts for nearly half of its total volume. Next is its leadership in Kazakhstan.

After getting Hess last year for $53 billion, Chevron is also a leader in emerging oil power offshore Guyana. The company shares a new, forced cooperation with the opponent Exxon, which first discovered Guyana a decade ago—maybe the biggest oil find of this century. But such major discoveries are rare in a mature industry.

The question is whether that will change now that exploration is starting again in South America, Africa, and other so-called frontier regions. In South America, international investments are increasing in Brazil, Argentina, Guyana’s neighbor Suriname—and now, possibly, Guyana’s other neighbor, Venezuela, now that the Trump administration is in place. controls its oil industry.

Exxon’s chairman and CEO Darren Woods touted its efforts in an October earnings call.

“With the (US shale) depletion curve, the industry must continue to think long term, invest, and find resources. That, I think, you are now seeing play,” said Woods. “People are seeing that resource and its horizon, and are moving into long-term, longer-cycle projects there.