Oil ministers of the 13-nation Organization of Petroleum Exporting Countries began their regular year-end meeting here today in an atmosphere of malaise and amid speculation they will cut some oil prices because of the continuing soft world market.

Winding up what outgoing OPEC President Subroto of Indonesia called "the most hectic year" in the cartel's two decades of existence, the world's main oil exporters resumed debate over the differentials charged for various qualities of oil.

At an emergency meeting in Geneva Oct. 29, OPEC agreed to reduce the spread between the benchmark and the highest price from $9 to $4 after months of wrangling. But the unprecedented glut on the world market -- which has led to a one-third cut in total OPEC production over the past two years -- continues a downward pressure on prices.

Saudi Arabian Oil Minister Sheik Ahmed Zaki Yamani, speaking to reporters, promised the pace-setting price of $34 for a barrel of Arabian light crude would be maintained until 1983, even if the value of the dollar fell and said he was thinking about "a little Christmas gift" for Western consumers.

He refused to say what the package might contain, commenting jokingly, "When you send a Christmas gift it has to be nicely wrapped and a surprise." The speculation, however, was that the producers were close to agreeing to an official reduction of $1 to $1.50 on a 42-gallon barrel of top-quality oil from the $38 maximum set in Geneva. The price of medium-heavy and heavy crudes, selling as low as $31.50 a barrel, might be reduced further.

Experts here estimated the reductions probably would help some of OPEC's hard-pressed producers to sell more oil while not significantly lowering the cost to the Western consumer.

The atmosphere of near-crisis reigning within OPEC was reflected in the opening speeches of both Subroto and the Emirates oil minister, Mana Saed Oteiba, who was elected president for next year.

Subroto said 1981 had been a "difficult year" and "a year of challenges" because of the two-year-long economic recession in the West and the glut on the world oil market of "a magnitude and duration to significantly test OPEC."

"I do not think it is too melodramatic to say that the pressure from these two tests brought about a severe tension in our organization," he said.

Oteiba said OPEC needed a period of "revision and reconsideration" of past experiences, including plans for adopting a long-term pricing strategy, if it were to go forward "with firm steps."

The sense of malaise within OPEC was heightened just before the conference opened by the breakup of a meeting of Arab oil ministers over the admission of Tunisia into the nine-nation Organization of Arab Petroleum Exporting Countries. Libya, which is blocking Tunisian membership over a disputed off-shore oil field, forced the meeting to adjourn before it could consider joint Arab oil policy.

The tensions within OPEC were also manifested in some of the comments of oil ministers at today's opening session.

Iran's representative, Mohammed Ghorazi, accused both the United States and Saudi Arabia of trying to sabotage the oil producers' cartel. Asked about the Saudis, the major OPEC producer, Ghorazi replied: "Anybody who tries to create an artificial market will be blamed by all the other members."

Saudi Arabia agreed at the October Geneva meeting to reduce its production by 1 million barrels a day. But its current level of 8.5 million barrels, about 45 percent of current OPEC production, is still judged too high by Iran, Libya, Algeria and Nigeria, which are trying to get higher prices for their oil than the current glut will permit.

Libyan Oil Minister Abdessalam Zaggar complained that Nigeria was charging too little for its top-quality, low-sulfur crude, undercutting Libyan and Algerian exports of similar-grade oil.

Nigeria, whose production plummeted from 2 million barrels daily last year to 700,000 barrels per day in August, has been making deals at $36.50 a barrel recently. In this manner, it has restored its exports to 1.3 million barrels per day. But this is $1.50 a barrel less than the fixed OPEC price for the highest-quality oil and $1 less than what Libya and Algeria are demanding.

Libya's production has dropped from 1.7 million barrels a day last year to 600,000 barrels daily in September. It is having difficulty getting companies to buy at $37.50.

OPEC production has dropped beyond all predictions by Western oil experts, from nearly 31 million barrels a day two years ago to less than 20 million barrels after the latest Saudi cut.

Although Western countries are consuming more than that level because of the winter season, the high level of stocks keeps prices soft. This explains why OPEC members charging the highest prices for the best-quality oil are still having trouble finding customers.

Even Kuwait is encountering difficulties selling its heavy crude at $33 a barrel. While it has set a production ceiling of 1.25 million barrels a day, it is actually able to find customers for only about 800,000 barrels.

Only Saudi Arabia, which has long charged the lowest prices among OPEC members, is experiencing no difficulty in marketing its oil. It is using its enormous leverage to force down prices and establish a long-term price-fixing formula.

The meeting here is expected once again to hear a report from Yamani on OPEC's long-term pricing strategy, but conference sources say there is little hope for any decision being taken before mid-1982.

According to Venezuelan Energy Minister Humberto Calderon Berti, the six-member Saudi-led committee on long-term OPEC strategy agreed at a preconference session on the principle of "flexibility" in handling the question of oil pricing in accord with the dictates of the market.

This comment seemed to raise questions about the ability of OPEC to establish a long-range formula in light of the experience of the past few months.