The nation's largest oil company dominated bidding in a $109.6 million lease sale yesterday as the government offered more than one million acres off the southeastern coast to oil and gas explorers.

Apparent high bidders were Exxon Corp. for 21 tracts off the coasts of Georgia and Florida, Tenneco Inc. for 13 tracts and Getty Oil Co. for 9.

But only eight companies participater in the first such sale of drilling rights off the southeastern coast, and they bid on only 57 of the 224 available tracts.

Government land managers atributed the apparent low interest to the offshore land being unexplored, but industry observers said oilmen shied away because thay felt the geologic conditions were unfavorable and were wary of a new government royalty system.

Bidders ignored available tracts off the Carolinas, concentrating instead on tracts from Savannah southward to Jacksonville, Fla. The land ranged from 30 to 75 miles offshore in waters 43 to 540 feet deep.

Government geologists say the area could produce between 280 million and 1 billion barrels of oil and from 1.9 trillion to 6.8 trillion cubic feet of gas.

Bids ranged from a low of about $140,000 to a high of $9.3 million offered by Tenneco for a tract east of Cumberland Island, Ga., in an area that brought other million-dollar bids.

Each tract contains more than 5,600 acres.

Total high bids were $109.6 million, although the government does not have to accept the high bid.

Leases will be awarded later by the secretary of the Interior after comparing the high bid to the government's own estimate of fair market value for the tract.

Exxon, which offered bids on 35 tracts, was the apparent successful bidder on 21 of them with a cumulative high bid of $34.4 million.

"We don't feel confident of the area. Finding oil is a high-risk, inexact science," said Robert W. Bybee, operations manager of Exxon's exploration department. "This is a high-risk, gambling business. But Exxon is large enough that we wanted to take the risk at this level,"he said.

Bybee said exploration could get under way within three months if the company secures the necessary permits.

Donald Truesdale, a deputy assistant director of the Bureau of Land Management, said yesterday's bids reflected the lack of exploration of the region, adding that the department was not disturbed that less than half of the tracts which received bids were sought by more than one company.

James Flug, an attorney for the Washington-based Energy Action Education of single bids on the tracts "dramatizes the problem we see" with the government's bidding process.

The Energy Action group had called on Interior Secretary Cecil Andrus to postpone the lease sale, claiming the oil industry would reap a windfall from the sale while the government received a pittance.

The government chose yesterday's sale to inaugurate a new royalty system for collecting money from oil companies in exchange for the drilling rights.

Eighty of the 224 tracts were covered by the experimental "sliding scale" royalty in which the companies must pay the government anywhere from 16.67 percent to 50 percent of the production value, based on the production volume.

The remainder of the tracts were covered by the standard 16.67 percent royalty system.

The bidding was to establish which company would pay the government the highest "bonus" for the drilling rights - money over and above the amount the government would receive in royalties.

The heaviest bidding competition was for tract 197 east of Jacksonville and about 68 miles offshore. Five companies bid for the rights to that tract, with Exxon submitting the apparent high bid of $5.7 million.

Other tracts in that area also went for several million dollars each.

The other companies in the bidding were Shell, the apparent high bidder on three leases; Sun Oil Co. of Delaware, apparent high bidder on four; Mobil, apparent high bidder on five; and Gulf.