All the elaborate oil-sharing plans of the world's industrial nations may be unworkable by the end of month.

The Carter administration delayed until last week submitting legislation that would extend key provisions of a law that allows 21 international oil companies to participate in the International Energy Agency's information and oil sharing plans without fear of antitrust charges.

Those provisions expire June 30, and with few members of Congress willing even to appear to be doing anything to aid oil companies, congressional sources say action by then is extremely unlikely.

And several of the companies say that without the expiring antitrust "defense" provision, they could not risk participating. "The answer is no, an emphatic, no," said an Exxon spokesman.

Without the extension, one top Energy Daptrement official said flately, "then you can't trigger" the sharing plans.

The plans call for the industrial nations to share available energy supplies if there is a supply interruption equal to 7 percent of normal demand.

Sweden has already sought to trigger the sharing plan because its shortage is at least that great. Other IEA member nations, with less of a shortage, have not been willing to set the machinery in motion, arguing that Sweden's shortage is due to its reliance on spot market purchases of oil last year when it was cheaper and readily available.

Adminstration officials are worried that the other IEA members are going to be "mighty upset" at U.S. procrastination and expect them to express their displeasure at an IEA meeting on June 25 and 26.

It could well become an issue, too, at the seven-nation economic summit meeting President Carter will attend in Tokyo June 27 and 28. Ironically the administration is pressing to pull together ideas for a new international cooperative response to the oil and shortage problem that could be agreed to at the summit session.

"We have been telling DOE for months that this was going to happen," said one oil company spokesman. "It can be awfully embarrassing to the U.S. government if this falls through a crack."

The energy Department also was warned as early as last February by members of the House Energy and Power Subcommittee that the DOE draft of the legislation then available would be difficult and time consuming to pass - partly because its several unrelated provisions fell into the jurisdiction of at least three seperate House committees.

Nevertheless, the draft sent to the Hill last week was still essentially in that form. As of yesterday, it had yet to be introduced in either the House or Senate.

"This is absolutely of prime importance," declared a State Department official who deals with IEA matters. "It's essential to the continued affective functioning of IEA." Failure to pass the extension would be "an extraordinarily serious blow," he said.

Getting the legislation passed, according to a Senate energy source, "will take a major effort, and no one has made it. There is too much suspicion and paranoia about the major oil companies."

Even DOE's enthusiasm for the legislation is questioned on Capitol Hill because of the department's insistence on putting the key provision into what DOE terms a "housekeeping" bill.

Some other sections deal with allowing the Energy Information Administration to file annual instead of quarterly reports for certain accounts, extending the time in which grants for energy conservation programs can be made to schools and hospitals, and clarifying the authority of the secretary of Energy to make awards for meritorious activities in the field of energy.

"There was no effort to smother it or bury it," responded an official in the general counsel's office at DOE. "It was just part of a legislative package."

Much of the delay involved getting the Office of Management and Budget to approve the draft legislation. OMB objected to some part of one of the less important provisions.

"It was unfortunate that we had that delay," said the DOE official. "We were considering separating the IEA part when OMB released the whole thing."

Top energy officials are concerned that there could be a replay of some of the debate that preceeded passage of the antitrust provision as part of the Energy Policy and Conservation Act in late 1975.

Fear of collusive acts by the oil companies led Congress to specify extremely rigid procedures for any meetings held involving the oil companies.