A Senate report drawing on subpoenaed oil company documents concludes that Saudi Arabia will limit its oil production in the 1980s to not more than 12 million barrels a day-a level so low it could touch off "a fierce political and economic struggle" among the consuming countries.

With a quarter of the world's oil reserves, and as the largest producer in the Organization of Petroleum Exporting Countries (OPEC), Saudi Arabia is one of the major determinants in whether or not the world will face an oil shortage in the 1980s. During the early 1970s American oil companies and the Central Intelligence Agency had expected the Saudis to increase their production capacity to 16 or 20 million barrels a day by 1985.

Although the Senate report does not say so explicitly, its findings indicate that while the Saudis have been willing to increase production within their present capacity to meet world demand, they have not moved to expand that capacity, as the United States has urged.

The report's major findings are:

Saudi Arabia is not expected to reach 12 million barrels a day in production capacity before 1987, let alone the 14 million barrels a day officials such as Energy Secretary James R. Schlesinger last year said they were likely to have on line by 1983.

Since it is not aggressively adding to its installed production capacity, Saudi Arabia will be in less of a position to apply downward pressure on world oil prices.

Forecasts for future oil discoveries in Saudi Arabia are "uncertain," although one Arabian American Oil Co. member says that as much as 33 billion barrels-roughly the size of current U.S. reserves-remain to be found there.

Aramco, a consortium made up of the Saudi government, Exxon, Texaco, Mobil, and Standard Oil Co. of Calif., has experienced "technical problems" in the fields since 1973-largely drops in reservoir pressures-that have forced it to revise cost and production projections.

The report says it found no evidence that Riyadh has set its production goal "to express displeasure" with the United States or other Western nations' policies in the Middle East.

There are strong "conservationist" attitudes guiding Saudi oil policy, based on a desire to stretch out oil reserves for future generations.

"Taking into account all these factors, it would be imprudent for the United States to plan on a change in Saudi Arabian oil development plans to increase long-term production above 12 million barrels a day," the report says.

The report, issued yesterday, has been the focus of a running political controversy dividing members of the Senate Foreign Relations subcommittee on international policy over arguments made by Exxon and Standard Oil Co. of Calif.-the two companies whose documents were subpoenaed-and Secretary of State Cyrus Vance that publication of the materials would offend the Saudis.

Exxon and Socal's internal materials were subpoenaed by the subcommittee, then chaired by Sen. Frank Church (D-Idaho), last August.

Before an executive session of the subcommittee convened last January, Vance made a personal appeal to Church, now the chairman of the full Senate Foreign Relations Committee, to not publish the report.

A similar appeal was made by Exxon Chairman Clifton Garvin and Socal Vice President Jones McQuinn during the January executive session. Both men said that making the Saudis' plans public could also undercut the position of U.S. companies operating there.

At a press conference on Thursday, Church said the subcommittee's decision to publish the report was taken "unanimously." Asked about pressure from the State Department not to make some of the data public, Church acknowledged that Vance had "raised questions I think the committee has been able to meet."

Church told reporters the strongest argument in favor of releasing the report is that, "We cannot formulate an energy policy without understanding the Saudis' role . . . There has been an assumption in the past that the Saudis had a valve they could turn."

Sen. Jacob Javits (R-N.Y.), the ranking minority committee member, said the report "introduces a note of realism" in setting energy policy.

During committee deliberations, Javits had argued with the companies and State Department against publishing a report, and against including subpoenaed material in the report.

At an executive session last Tuesday other subcommittee members, including Chairman Paul Sarbanes (D-Md.), George McGovern, (D-S.D.), Joe Biden (D-del.), and Richard Lugar (R-Ind.) agreed to publish a final report under a compromise assuring that it would not refer to subpoenaed documents or quote from them. Javits and Biden opposed publishing earlier versions of the report.

Among details excluded from earlier drafts were accounts of conversations between Aramco Executives and Saudi Oil Minister Ahmed Zaki Yamani and other Saudi officials over the condition of the oil fields and Saudi concern about extending the life of the oil fields.

Javits told reporters, "These are the staff's conclusions . . . not to be attributed to anyone else." Normally, staff Reports are issued as the expressions of the views held by committee members.

The State Department said, "This report does not represent administration views."

Saudi Arabia is the world's leading oil exporter, producing 8.5 million barrels a day, and is the largest oil producer among the 13 members of OPEC.

The United States receives 17 percent of its imports, or about 1.6 million barrels a day, from the Saudis. Of all the oil exporting nations, however, Saudi Arabia has been the most crucial to sustaining production to meet world needs since the 1973 Arab oil embargo. President Carter and his predecessors have said that United States policy towards the Persian Gulf is in large measure dictated by Saudi Arabia's self-proclaimed role as OPEC's most "moderate" producer.

The Saudi government has had no comment on the report.

In a phone interview yesterday, however, former U.S. ambassador to Saudi Arabia James Akins said: "The Saudis are not going to like it very much. They consider the details of their oil policy proprietary information." Akins added, that "the conclusions are valid. Aramco may have counted on 16 million barrels a day, but the Saudis never did."

Disagreeing with one statement in the report, Akins declared: "The Saudis have explicitly tied production to politics from 1973 up to date."

Exxon issued a statement Friday calling the report "very regrettable . . . This type of information has long been considered by the Saudi government as highly confidential."

And Socal's McQuinn said in an interview, "The issuance of this of a report could well be misunderstood in terms of the U.S.-Saudi relationship."

The 30-page report details technical contraints in the Saudi fields, including the giant Ghawar field, that would require billions of dollars in new facilities not anticipated by Aramco or the Saudis as recently as 1975 or 1976, in order to significantly increase production capacity.

Ghawar, nearly the size of the State of Delaware, is the world's largest field and accounts for 10 percent of world oil reserves. The Saudis have concluded "that Ghawar in the past has been overproduced" by the Armaco companies, the report says.

The report also itemized pressure drops in parts of Ghawar and other major Saudi fields, such as the Berri field that some petroleum engineers have argued, could reduce the amount of oil that ultimately can be pumped from the ground.

Aramco Chairman John Kelberer has denied this repeatedly in the past.

Aramco, under Saudi instructions, is planning on production not exceeding 12 million barrels a day which "may last for 15-20 years before irreversibly declining, a period Saudi Arabia now finds uncomfortably short," the report says.