The chilling specter of armed conflict between America's two most important oil-producing allies - Iran and Saudi Arabia - has found its way out of popular fiction and into serious study in a Senate committee report released today. The report suggests that the United States should condone an Iranian invasion of Saudi Arabia in certain circumstances.

"If Iran is called upon to intervene in the internal affairs of any Persian Gulf state, it must be recognized in advance by the United States that this is the role for which Iran is being primed," the Senate study says. "Blame cannot be assigned for Iran's carrying out an implied assignment."

The report prepared for the Senate Committee on Energy and National Resources, chaired by Sen. Henry M. Jackson (D-Wash.), argues that the United States has "a direct interest" in ensuring that Iran has sufficient military capabilities to prevent the Soviet Union or radical forces from taking power in any of the oil-rich Gulf states, especially Saudi Arabia.

The outlines of the report, written at Jackson's request by consultants Fern Racine Gold and Melvin A. Conant, resemble the fictional political thriller. "The Crash of '79," which portrays and Iranian invasion of Gulf oil-field triggering worldwide economic collapse.

But the report's implications are far more political than literary. Jackson is an avowed champion of both Israel and Iran, two countries whose supporters are showing increased concern over the Carter administration's growing reliance on Saudi Arabia's oil supplies and financial reserves.

Jackson is expected to lead a Senate fight next year to deny Saudi Arabia the right to buy 60 F-15 fighter-bombers promised by the administration.

While arguing that the United States has an interest in Iran's "military strength," the report offers no such endorsement for Saudi Arabia. Moreover, it places "political stability" in Saudi Arabia as "a complementary interest" for the United States, after the primary goal of "maintaining access to the vital oil reserves of Saudi Arabia."

The United States imports from Saudi Arabia 25 per cent of the 8.5 million barrels of oil it consumes daily. Iran provides 6 per cent of American imports.

Production in Iran which has embarked on an ambitious but still faltering economic development program and which had built up one of the world's most sophisticated military machines, is falling. Saudi Arabia, which has a small, poorly trained army, sits atop the world's richest pool of oil reserves.

In a summing up of the "implications" of U.S. Iranian ties, the authors of the report appear to try to soften the impact of their strategic analysis by pointing out that "the United States is not committed to resupply Iran with military equipment or parts in the event of an Iranian military action which does not serve U.S. interests."

But the pro-Iranian thrust of the report is reflected by the fact that, although in the original draft, obtained by The Washington Post, the authors had added. "Iran does not have a tree hand must not have one," those words were struck from the version issued by Jackson.

Saudi Arabia and Iran accounted for 44.6 per cent of the United States' $8.7 billion in foreign military sales last year. Iran and Israel are the first and second largest purchasers of U.S. arms, followed by Saudi Arabia. Much of the Saudi purchasing, is devoted to building infrastructure projects such as airports.

Calling the American dependence on oil imports from the two largest oil exporting states "unpecendented," the analysis says the United States should be watchful for differences between the Saudis and their non-Arab neighbors across the Persian Gulf in Iran.

While both Iran and Saudi Arabia are essentially pro-American and share Islamic values, the two countries have had an uneasy relationship during recent years.

The shah, for example, has cultivated close relations with Israel and is Israel's largest oil supplier.

Tehran and Riyadh have also disagreed violently on policy in pricing battles in the Organization of Petroleum Exporting Countries (OPEC) in recent years. Iran has consistently fought for higher prices, citing its development needs and the ability of the West to pay higher prices, while the Saudis have worked for price freezes to give Western economies a chance to recover from the global recession of the mid-70s.

The report portrays an inevitable stability in Iranian oil policy but expresses doubt about Saudi Arabia's situation. A change in government in Iran is "unlikely to affect the flow of oil. The revenue needs of any Iranian government will be such as nearly to compel it to produce at highest possible rates."

A change in Saudi Arabia, on the other hand, "could result in a drastic reduction in the volume of oil entering world trade" because of Saudi Arabia's ability to live on its $29 billion reserve assets for a long period. By implication, the report portrays such a moment as the time for Iran to be primed to take action in the Gulf, ostensibly on America's behalf.

Saudi Arabia's oil reserves are at least three times larger than Iran's. Iran has the capability to produce up to 6.7 million barrels a day, compared to more than 10 million barrels a day for Saudi Arabia. More important, Saudi Arabia could produce up to 20 million barrels of oil a day in the 1980s, after Iran's oil production has peaked.