BOSTON (Reuters) - Taking his private equity firm public paid off big for Blackstone Group LP’s Stephen Schwarzman, who became the top-paid chief executive in the United States last year, a title he is likely to retain for some time, according to an analysis released on Thursday.

But the surest route to big bucks was running an oil or natural gas company. Their CEOs represented seven of the 10 highest-paid U.S. CEOs in 2008, according to a report by independent research group The Corporate Library.

Schwarzman bumped Oracle Corp’s Larry Ellison down to No. 2 on the list. They were followed by seven oil CEOs and Michael Jeffries, head of teen apparel retailer Abercrombie & Fitch Co.

The year stood out for the amounts the top-paid executives received, as seven people secured total compensation of more than $100 million. Just three made that much a year before and two of them were retiring CEOs, said Greg Ruel, a Corporate Library research associate who coauthor the report.

Ellison’s compensation, for instance, soared to almost $557 million, from $192 million.

Another major shift was how few executives outside the oil and gas industry made the list.

“It’s so filled with petroleum executives,” Ruel said, adding that the result reflected executives cashing in on stocks that until last summer were still chasing oil’s rally to a record high near $150 a barrel.

The study ranks CEOs on “total realized compensation,” which includes cash pay and bonus, perks, plus the value of stock options exercised and the vesting of restricted shares, Ruel said.

FOUNDERS TOP THE LIST

The vast bulk of Schwarzman’s pay -- $699.8 million of a total $702.4 million -- reflected the vesting of equity grants he received when the company went public in 2007. The vesting will continue over the next four years.

“It is reasonably safe to assume that Mr. Schwarzman will remain at the top of (the) highest paid CEOs list, or close to it, for a few years to come,” the report says.

It notes that given his status as founder of the company much of the pay reflects his initial investment in Blackstone.

But Blackstone disputed this should count as compensation.

“This is absurd,” said Blackstone spokesman Peter Rose. “At the time of the IPO, Steve (Schwarzman) received stock in exchange for his partnership interest in Blackstone. This vests over a number of years. In no sense does the stock he owns as it vests become compensation.”

Schwarzman had a base salary of $350,000 for 2008 according to a regulatory filing in March.

Oracle’s Ellison brought in almost $557 million, with some $543 million coming from exercising stock options in the No. 3 software maker.

Company founders tend to top the list, Ruel said.

The oil executives in the top 10 racked up big gains from stock options.

The CEOs of Occidental Petroleum Corp, Hess Corp, Ultra Petroleum Corp, Chesapeake Energy Corp and XTO Energy Inc all took in more than $100 million in total realized compensation, while the heads of EOG Resources Inc and Nabors Industries Ltd received eight-digit awards.

The companies that fell off the top 10 were eBay Inc, Target Corp, WR Berkley Corp, MEMC Electronic Materials Inc, AFLAC Inc, IntercontinentalExchange Inc, Goldman Sachs Group Inc, Capital One Financial Corp and United Technologies Corp.

“It’s not a surprise that this year there aren’t any financial or insurance companies” in the top 10, Ruel said.