Oil production has begun falling at all of the major Western oil companies, and they are finding it harder than ever to find new prospects even though they are awash in profits and eager to expand.

Part of the reason is political. From the Caspian Sea to South America, Western oil companies are being squeezed out of resource-rich provinces. They are being forced to renegotiate contracts on less-favorable terms and are fighting losing battles with assertive state-owned oil companies.

And much of their production is in mature regions that are declining, like the North Sea.

The reality, experts say, is that the oil giants that once dominated the global market have lost much of their influence — and with it, their ability to increase supplies.

“This is an industry in crisis,” said Amy Myers Jaffe, the associate director of Rice University’s energy program in Houston. “It’s a crisis of leadership, a crisis of strategy and a crisis of what the future looks like for the supermajors,” a term often applied to the biggest oil companies. “They are like a deer caught in headlights. They know they have to move, but they can’t decide where to go.”