President Reagan's authority to impose oil-price controls or to allocate supplies of crude oil and to ration gasoline expires today.

In the immediate world of plentiful oil supplies and falling prices, expiration of the authority will hardly matter. No major interruptions of oil supplies, such as occurred during the Arab embargo of 1973 and in the aftermath of the Iranian revolution in 1979, are looming anywhere in the world.

Nevertheless, Congress is moving to give the president a new grant of power to impose price and allocation controls, which he has said he does not want or need. Backers of the bills in both the Senate and House energy committees, however, are convinced Reagan will not veto the new legislation once it clears Congress. Should the president sign it, of course, he would be in the position of accepting the use of price controls, which he has strongly opposed.

Administration officials have testified against the legislation, arguing that the president already has ample authority to act in the event of a supply emergency. However, an internal administration memo obtained by the Senate Energy Committee indicated that both the Justice and Energy departments had strong reservations that sufficient authority will remain after today.

Price controls were imposed on virtually the entire economy, including the oil industry, by President Nixon in 1971. In November 1973, as other price controls were being lifted, the Arab embargo led to passage of the Emergency Petroleum Allocation Act, which created the Federal Energy Administration and gave it price control authority and the power to allocate supplies. After the authority nearly lapsed late in 1975, it was extended by the Energy Policy and Conservation Act. Under the terms of EPCA, President Carter began phasing out controls in 1979, and Reagan completed the job last January in one of his first acts as president.

The Senate Energy Committee may complete work on its version of the legislation today, according to committee staffers. Issues remaining to be resolved include the extent to which the bill should preempt laws in more than 20 states that deal one way or another with oil shortages, and whether to set any terms for use of oil from the strategic petroleum reserve -- which now has nearly 200 million barrels of crude oil in storage.

Only agriculture and defense are mentioned as specific priority uses of fuel that the administration must consider in setting allocations. The bill also plays down the use of price controls, indicating they should be used only to the extent necessary to make allocations work.

On the House side, the fossil fuel subcommittee probably will take up the bill within two weeks, a committee staffer said. The emphasis there, too, is in producing a "simple" bill providing controls authority without specifying exactly how it should be used. "It is your basic emergency, rock-bottom price and allocation bill," the staff member said.

Smaller oil companies, refiners, marketers and many oil users have tried to persuade the committees to include language giving them some advantage in an oil emergency. The independent refiners, for example, have pushed for a requirement that major oil companies be forced to share their crude supplies with the smaller companies.

The administration has said repeatedly that it intends to rely on the marketplace to deal with any shortage -- with higher prices reducing demand -- unless the lack of oil is so great that it threatens national security. Price and allocation controls made the 1979 situation, in which motorists in many parts of the nation faced lengthly gasoline lines, worse instead of better.