OPEC ministers meeting on Tuesday were widely expected to keep output targets steady for now, but could act soon to prevent excess supply weighing on the market.
Oil prices, which hit an all-time high of $147.27 in July, have fallen by nearly 30 percent to a five-month low of less than $105 a barrel, the weakest since early April.
Ministers of the 13-member Organization of the Petroleum Exporting Countries (OPEC), who blamed speculation for the run-up to record levels, have said the price now reflects market fundamentals.
"I think everything is in balance — inventories are in a healthy position," Saudi Oil Minister Ali al-Naimi said on arrival in Vienna in the early hours of Tuesday morning.
They were his first public comments since July.
OPEC's meeting in Vienna, which is not expected to begin until around 9 p.m. local time (1900 GMT) because of Ramadan fasting, is the group's first official gathering since March.
But Saudi Arabia, the world's leading exporter, called an emergency energy meeting in Jeddah in June to address what then seemed to be runaway prices.
The kingdom unilaterally announced it would pump 9.7 million barrels per day (bpd), around 750,000 bpd above its OPEC production ceiling, although some analysts have said it has pumped below that level.
"The market is fairly well-balanced and we have worked very hard since the June meeting to bring prices to where they are now. I think we have been very successful," Naimi told reporters.
FLOOR AROUND $90-$100?
Saudi Arabia has always been careful to avoid stating a target price, but a senior OPEC source close to Gulf countries was quoted in the Saudi-owned daily al-Hayat as saying market fundamentals indicated price levels of around $90-$100 a barrel.
That price is roughly in line with levels cited by other OPEC members, including Iran, which has been at the forefront of those wanting to curb excess supply.
"Of course, of course. I believe that the market is over-supplied," Iranian Oil Minister Gholamhossein Nozari told reporters on arrival in Vienna on Monday.
But even Iran could settle for tighter compliance with existing targets for now.
OPEC's Ministerial Monitoring Committee, which met late on Monday and included Iran, would recommend compliance with existing output targets to the group's plenary session on Tuesday, delegates told Reuters.
As a whole, OPEC is estimated to be producing roughly 790,000 bpd above a collective ceiling of 29.67 million bpd for its 12 members with output limits.
OPEC's President Chakib Khelil set the stage for a possible output revision at OPEC's next planned meeting, which he will host in Algeria in December.
"We're going to have an over-supply by the end of year," said Khelil, who is also Algeria's energy and mines minister.
The surplus could be anything from half a million to 1.5 million bpd by early next year, he added.
Delegates also said OPEC was debating whether to call an extra meeting between now and December to reassess the supply-demand balance.
