Twice in the last 17 years, the Organization of Petroleum Exporting Countries has held the world in thrall, taking advantage of crises in the Middle East to jack up the price of oil and hold industrialized nations as economic hostages.

Now the Middle East is in turmoil again -- but so is OPEC. One of its members has invaded another after fighting an eight-year war with a third, upsetting the group's delicate political balance. At the same time, OPEC has lost control of the world oil market to commodities traders in New York -- while the price of crude oil has nearly doubled in the past few weeks, the increase has more to do with whims of the futures market than OPEC's once-firm hand.

The 13 members of the most powerful cartel the world has ever known haven't even been able to decide among themselves whether to meet to discuss the situation. Saudi Arabia, OPEC's largest member, said Saturday that it was ready to break with the cartel and increase its daily oil production of 5.38 million barrels by 2 million barrels in an attempt to calm oil markets. Other members are expected to follow, despite protests from about half the group's members. The Saudis said they hope OPEC will meet this week to approve the increases.

Although there always have been political and economic divisions within the cartel, longtime OPEC watchers can't recall when the 30-year-old organization has been so fragmented. And they suggest that the oil cartel may never be the same. Where OPEC, by charter, once moved with unanimity -- or some semblance of it -- to influence world oil prices and supply, analysts said the cartel now appears to be an organization in which a majority will rule -- and the votes will be close.

"OPEC, as we knew it, has ceased to function," said Lawrence J. Goldstein, president of the Petroleum Industry Research Foundation in New York. "I think you're going to see a new consensus organization develop. Nothing is permanent, but you have to use what is usable."

It probably is too early to write OPEC's obituary, however. The group of oil producers in the Middle East, Africa, South America and Asia has been counted out before, only to be revived and reunited by changing political winds and economic necessity. And with control of nearly half the non-communist world's oil output, OPEC's various members seem likely to continue to be major players in the world oil market, together or separately.

But OPEC clearly is at a crossroads, one that experts say has been developing for some time.

After dramatically raising prices in the oil crises of 1973 and 1979, OPEC has found in recent years that adjusting the flow of oil production is just as effective a weapon as pricing. That has changed the power structure of the cartel, giving large producers such as Iraq, Saudi Arabia and Venezuela clear-cut dominance over smaller countries like Qatar, Gabon and Ecuador.

With that shift has come a battle for OPEC leadership between Iraq and Saudi Arabia. The fight is exacerbated by Iraq's annexation of Kuwait, which potentially gives Iraq oil reserves and production capability nearly as great as those of Saudi Arabia.

When OPEC last met in late July, shortly before Iraq invaded Kuwait, Iraq succeeded for the first time in memory in winning its way over the Saudis. It gained OPEC approval to raise the basic price of a barrel of oil to $21 from $18 -- the price since has jumped to more than $28 because of the market run-up since the Aug. 2 invasion -- and won production quotas for OPEC's members designed to support such a price over time.

Most analysts saw Iraq's victory in the July 27 meeting as a turning point. And Iraq's new-found control over OPEC was hammered home by its invasion of Kuwait earlier this month, an attack largely motivated by Iraq's pique at Kuwait for violating OPEC production quotas by pumping more oil than was authorized by the cartel. Together, Iraq and Kuwait produce 9 percent of the world's oil.

In the past, OPEC's production quotas have been fairly flexible. Though codified by the organization, the quotas frequently have been violated by members with their own agendas and enforcement usually has consisted of other members adjusting their production to keep overall output levels in line.

Saudi Arabia, for instance, has raised its production several times in recent years to make up for output reductions by other, more hawkish members hoping to raise prices by decreasing supply.

But Iraq's invasion of Kuwait to enforce the OPEC production quota represented a new level of enforcement. "The invasion is certainly a lot worse than anything else we've seen," said Michael C. Lynch, an analyst at the Washington International Energy Group.

Lynch and others noted that while Iraq and Iran were locked in war for most of the 1980s, they weren't fighting over oil, and representatives of the two nations continued to deal with each other, albeit tensely, at OPEC meetings.

The market-price increase following the invasion also effectively gave Iraq what it wanted when it sought a $25-a-barrel price at the July meeting.

Iraq is one of OPEC's price hawks, who want to exploit the economic benefits of their oil reserves as quickly as possible, while doves like Saudi Arabia argue for a long-term strategy and fear that too-high prices can cause a worldwide recession that would significantly reduce demand -- and prices -- for years to come.

The Saudis' recent attempts to raise production to make up for the oil lost because of the invasion of Kuwait and the resulting blockade of Iraq reflects this more moderate philosophy.

"Those countries that have high capacity and high reserves have always said, 'We can make up any difference in volume,' " said Vahan Zanoyan, an OPEC expert at Petroleum Finance Co., a Washington consulting group. "Those who don't have the high capacity say, 'The hell with it. Let's make it now while we can, even if oil goes to $100.' "

This difference in philosophy underlies OPEC's difficulty in gathering to even discuss the current situation. Despite repeated calls from Saudi Arabia and Venezuela for a meeting of the cartel, many other members, led by Iraq, are happy with the high prices and have balked at discussing anything that would reduce them.

The Saudis, Venezuelans and others had hoped to win OPEC sanction to increase production beyond quotas to make up for the missing Iraqi and Kuwaiti oil. OPEC approval would provide them with political protection against the wrath of Iraq and other more hawkish members. By raising production on their own, analysts say, these nations are further deepening the split in OPEC.

The division is likely to continue, experts say, as Saudi Arabia and Iraq carry on their tug of war for OPEC dominance.

"OPEC's in a position, as an organization, of saying, 'Who's the boss? Who's going to win out in this competition, Iraq or Saudi Arabia and its friends?' " said Joseph Story, president of Gulf Consulting Group in McLean.

OPEC's future decision-making processes likely will reflect the split, with the organization divided pretty well down the middle between hawks and doves. Ironically, Kuwait may wind up as something of a tie-breaker, depending on whether OPEC decides if it still is a sovereign state or part of Iraq, which would reduce membership to 12.

Should Iraq succeed in keeping Kuwait and resume oil exports, OPEC's power balance will be forever changed, according to a top executive of a major U.S. oil company. "They would be the dominant power in OPEC and they would pretty much set what the world price would be," the executive said.

In any event, OPEC seems destined for change, regardless of the outcome of the crisis.

"I think a new animal will evolve after the resolution of the {present crisis} situation," said Joseph Stanislaw, managing director of Cambridge Energy Research Associates, a Boston-based consulting group. "Key players will be dominant and key players will be more highly motivated than they have been."

"You're going to definitely have a changed power structure within the organization when all this settles," said John Redpath, an oil analyst at Energy Security Analysis Inc. in Washington. "But you're still going to have an OPEC."