In the wake of the U.S. Supreme Court's imprimatur on the exploration for oil under the Atlantic outer continental shelf, a small flotilla of drilling rigs is being marshaled in the Gulf of Mexico to make a snail's pace journey 1,500 miles northward.

In a matter of weeks, the first six offshore rigs will be ensconced closer than ever before to the Boston-Washington megalopolis, bringing with them fears of environmental blemish and hopes of economic salvation.

But as the big oil companies stand poised to exploit the wealth of petroleum and natural gas they presume exists in the Baltimore Canyon Trough there is scant evidence that much of those riches will stick anytime soon to the mid-Atlantic region where the offshore drilling sites are located.

The flood of jobs and money that was predicted to flow into the Northeast once offshore drilling began is beginning to look more like a slow trickle now that the final go-ahead has been given.

For the time being, at least, the lion's share of the employment and capital investment will benefit the Gulf Coast and not the seaboard states from Rhode Island to Delaware where the exploration will occur, according to officials of the participating oil companies.

What's more, even if oil and gas are found under the Atlantic, it will be seven or eight years before any measurable effect is felt in the economy of the Northeast -- and especially Rhode Island, where the oil firms' staging operations are concentrated, state economic development officials said.

In a few weeks, contractors for the first six oil firms to receive permits will begin towing leviathan, semi-submersible drilling rigs from the Gulf of Mexico over the 1,500 or more miles to the Baltimore Canyon trough. Exploratory drilling for most of the major oil firms will begin in mid-April.

Officials at Ocean Drilling and Exploration Co., in New Orleans, the largest offshore contractor, said the big rigs can move no faster than seven miles an hour. The firm has 22 rigs in the Gulf of Mexico, and currently is negotiating leases with some of the major oil companies involved in the Baltimore Canyon exploration.

The Supreme Court last week turned down an appeal aimed at delaying the start of drilling 47 to 92 miles off New York, New Jersey and Delaware. Last August, the Interior Department accepted bids of more than $1 billion for lease of 93 tracts covering 500,000 acres.

The U.S. Geological Survey has estimated that between 10 billion and 20 billion barrels of oil and between 53 trillion and 110 trillion cubic feet of natural gas ultimately may be found beneath the shelf, although those estimates are highly uncertain.

When the major oil firms argued their case for drilling rights, they said they anticipated that employment in the exploratory phase would be more than 2,000 people, and would peak at between 4,500 and 9,000 workers. They also observed that capital expenditures would rise to a total of $1 billion.

To Rhode Island, which has been suffering from the debilitating effects of military base closings and from an unemployment rate that often has been double the national average, the news seemed like a financial bonanza.

Surplus piers at the former Quonset Point Navy facility at Davisville, R.I., were envisioned as a huge staging base for the 39 oil companies that purchased leases, along with suppliers and various support companies needed to service the offshore rigs.

Public officials talked expectantly about a boon for the region's economy, if on the courts would settle the environmental issue and allow the oil companies to begin their exploratory drilling.

The dream of a windfall of jobs and money is still alive, but slightly less grandiose as the moment of actual drilling is at hand.

"We're trying to play that down right now. The economic impact of the work force is not as large as a lot of people would like to think," said a spokesman for Gulf Oil Co., at the firm's Houston headquarters.

Other oil company officials and Rhode Island economists said the same thing -- that the northeast lacks a pool of available experienced offshore drillers and roustabouts, and that for some time, at least, the payroll will go mostly to workers imported from Louisiana, Texas and Mississippi.

Much of the money will even be spent out of state. The larger rigs have 80-person crews that split 12-hour shifts and work 14 days and have 14 days off. Most of them can be expected to fly to their home Gulf states for their time off, the oil company officials said.

Moreover, most of the capital investment will initially go to the offshore drilling contractors along the Gulf Coast, who lease their $50 million rigs to the oil companies for about $70,000 a day.

Gordon Byrd, acting director of the Rhode Island State Department of Economic Development, conceded that he "doesn't expect any amazing job buildup now. The big buildup we're hoping for will be if they find sufficient quantities of oil, and that will be some years away.

"You can't send inexperienced crewmen out onto rigs in the North Atlantic and get them killed just because Rhode Islanders need jobs. It will take at least seven years for any effect to become significant, maybe longer," he added.

But Byrd said that if large reserves of oil are discovered, the state would gradually become a beneficiary because production rigs and other heavy equipment could be constructed locally.