U.S. ENERGY SECRETARY OPTIMISTIC ON INCENTIVES U.S. Department of Energy Secretary John Herrington said he was "optimistic" about the chances of providing a more generous depletion allowance for oil and gas producers, but added that the plan faces strong opposition from some members of the Reagan administration. Herrington, speaking to Houston oil executives at a breakfast meeting, said administration debate over his plan for a 27.5 pct annual depletion allowance was "heavy and strong" largely because of some fears that the U.S. oil industry could eventually become as dependent on federal subsidies as the agriculture industry. Herrington's proposed tax incentives for the oil industry were issued last week after the Department of Energy released a comprehensive report finding U.S. national security could be jeopardized by rising oil imports. In response to a question from Mitchell Energy and Development Corp <MND> chairman, George Mitchell, Herrington said the report did not definitively rule out an oil import tarrif. "We intend to keep that debate open," Herrington said. However, following his speech, Herrington told Reuters that the new report shows an oil import fee "is not economical." Herrington said, for example, a 10 dlr per barrel tariff on oil imports would cause the nation's gross national product to drop by as much as 32 billion dlrs. Herrington also said he believed President Reagan, who requested the comprehensive national security study, was committed to some action to help the ailing U.S. oil industry. "I'm quite confident he understands the problems and is prepared to do something about it," Herrington said.