Rainwater's energy venture running out of gas. (Richard Rainwater's Wolverine Exploration Co.)(includes company profile)

Richard Rainwater once confessed that he feared his investments would become "going-out-of-business stories" in the 21st century.

The multimillionaire cowboy capitalist from Fort Worth might not have to wait that long.

Wolverine Exploration Co., an oil and natural gas company that Rainwater rescued in 1987, is putting him in an unfamiliar position: teetering on failure.

Although not long ago it looked like Rainwater had tapped into a gusher of revenue, Wolverine now says that its biggest well has gone dry and that bankruptcy looms if the company's banks are not willing to renegotiate $20 million in debt.

In effect, Wolverine has reverted to the sort of company that Rainwater bailed out.

But for a longtime follower of the man Forbes magazine ranks among the richest people in America does not expect Rainwater to step between Wolverine and the banks …