12 Oil Firms Sue Over Drilling Ban : Energy: They say the government refused to let them develop the leased sites. A judgment could cost $1.5 billion.

A dozen U.S. oil companies are suing the federal government for selling them offshore oil leases, then banning drilling on the sites. Reimbursing the companies could cost taxpayers up to $1.5 billion, according to Interior Department estimates.

Chevron Corp., Mobil Corp., Texaco Inc., Unocal Corp. and seven other companies filed suits Wednesday in U.S. Claims Court in Washington accusing the federal government of breach of contract and other transgressions for stopping oil development on leased sites on the outer continental shelf off California, Florida, New England, North Carolina, Oregon and Washington. Conoco Inc. had filed a similar suit last May seeking $37 million in expenses and interest.

The companies charge that after they invested millions in lease purchases, seismic studies and other preparations, the areas were put off bounds. President Bush in June, 1990, banned new drilling off 99% of the California coast and environmentally sensitive offshore sites in the other states until the year 2000. Republican supporters at the time said this validated Bush’s claim that he was the “environmental President.”

Chevron, based in San Francisco, is suing for $100 million for investments in leases off Florida, North Carolina and Alaska. Unocal wants more than $71 million for leases in the same areas. Mobil is suing for $183 million.

Some oil companies have reportedly said they will seek reparations not only for money already paid in leases but also for oil and gas revenue that they might have reaped without the ban.

While industry sources told the Associated Press that the suits would total more than $600 million, the Commerce Department estimates the potential liability at almost three times that.

Many environmentalists favor giving the companies limited pay-backs or lease exchanges for their investments, though they oppose paying them for potential oil revenue lost because of the ban. Bruce Hamilton, conservation director of the Sierra Club, said buying a lease does not convey the right to develop.

“In some of these offshore oil leases where they are putting down $10 million and $20 million,” Hamilton said, “they have a good argument to at least reclaim the money they put down for the lease. But not the speculative value.”

The companies filing Wednesday--which also include Amoco Corp., Amerada Hess Corp., Marathon Oil Co., Murphy Oil Co., Occidental Petroleum Corp., Pennzoil Co. and Shell Oil Co.--were waiting to see whether a pay-back provision remained in the new energy bill signed by Bush on Saturday. But that provision was not included in the bill’s final version.