For more than six months, the Senate Foreign Relations Committee has been methodically studying the conditions of Saudi Arabia's oil fields.

Unlike most congressional inquiries, this study's conclusions, due out this week, are being anxiously eyed by a high-level array of interests including: Secretary of State Cyrus R. Vance, Energy Secretary James R. Schlesinger and Central Intelligence Director Stansfield Turner, along with oil and political analysts within the CIA.

Beyond that, four major oil companies -- Exxon, Standard Oil of California, Mobil and Texaco -- that make up the Arabian American Oil Co. are also apprehensively awaiting the publication.

Perhaps the most sensitive expectants will be the members of the Saudi royal family and the circle of technocrats that preside over the nearly 10 million barrels of oil Riyadh ships daily to the world market.

Sources say the Senate report will conclude in part that the Saudi oil fields, the world's most prolific, have declined since production began in 1938 and that, as oil has flowed to world markets, the fields have experienced pressure drops. The panel's findings are based on thousands of pages of subpoeaned documents obtained from Exxon and Standard Oil of California by the subcommittee on foreign economic policy last year.

In recent months Vance has privately urged Committee Chairman Frank Church (D-Idaho) not to release the study. The State Department fears further friction in the somewhat strained relations with Riyadh. Sen. Jacob Javits (R-N.Y.), ranking minority committee member, has made a similar argument, adding that the subpoenaed company documents were not intended for publication.

Sources close to these discussions, however, raise still other aspects of the Saudi oil field debate. On Chriostmas Day 1977 a New York Times article reported that the Saudi fields were "mismanaged" and in ill repair, based on interviews with "leading energy experts," later reported to be CIA analysts.

Saudi Minister of Petroleum Sheikh Zaki Yamani charged that the Cia/ was seeking to minimize the immediate productivity of the Saudi fields because this supported the agency's forecasts of a severe energy shortage in the 1980s. Aramco executives deny that there are any unusual or abnormal pressure drops in the fields. "Each of our shareholders and the Saudis independently monitor the reservoir pressure,c says James Knight, Aramco's Washington vice president. He says the fields are well maintained and capable of producing more than 10 million barrels a day.