ALGIERS—OPEC members and Russia have substantial issues to work out before making a deal to limit oil production, but still expect to make progress toward a comprehensive deal, energy ministers said.

Algeria's oil minister, Nourredine Bouterfa, said there was still a chance a deal could be sealed this week when the Organization of the Petroleum Exporting Countries meets on the sidelines of a conference here. But Mr. Bouterfa, one of the biggest advocates of new limits on OPEC production, acknowledged that the meeting may produce only "the elements of an agreement."

"We can't come out empty-handed," Mr. Bouterfa said, warning that oil prices could drop from $45 a barrel today back into the $30s if OPEC fails to come to terms this week.

Mr. Bouterfa's comments Sunday signaled that even if OPEC fails to reach a deal this week, the 14-nation cartel will continue talking about curbing production this fall as it heads into its next official meeting in Vienna on Nov. 30. OPEC Secretary General Mohammad Barkindo said a week ago that the meeting was for consultations only, not for a decision. He later clarified that the cartel could reach a deal later if a consensus emerged.

Delegates in the cartel have said the Algiers meeting is aimed at starting discussions they hope will lead to an agreement at the formal OPEC meeting in Vienna.

OPEC, whose members control more than one-third of the world's petroleum production, and other big oil producers have been struggling to respond to historically low oil prices. The slump was caused by a boom in U.S. production from shale formations. OPEC's de facto leader, Saudi Arabia, has responded with record levels of output of its own instead of its traditional tool of production cuts.

In an interview, Nigeria's oil minister, Emmanuel Ibe Kachikwu, said he supported a production freeze but said Saudi Arabia had "very strong" reasons for increasing its output. With U.S. producers able to raise output quickly when prices rise, "even if we have a freeze, what difference does it make?" Mr. Kachikwu said.

"Someone will just move in and take over that market share. Whether at the end of the day the freeze itself will be sufficient to impact the market in a way that we expect is also still questionable."

Mr. Kachikwu said his country couldn't freeze its production now because Niger Delta militants have sabotaged its pipelines, lowering output. He said Nigeria would have to be exempted if there were a freeze.

Other countries that include Iran and Libya are also looking for exemptions from a freeze until their production comes back to full strength.

A similar effort to agree on an output cap failed in April in Doha, Qatar, after Saudi Arabia demanded that Iran join it. Iran is trying to increase its production to four million barrels a day following the end of Western sanctions that crippled its oil industry for more than three years.

According to people familiar with Saudi Arabia's plans, the kingdom doesn't want to make a formal agreement until November.

OPEC is considering four options that have the cartel's members and Russia freezing at production levels reached in January or August 2016 or at the average of the first quarter or first half of 2016. All of those scenarios would involve Iran freezing at levels below its pre-sanctions' output, the people said.

"Everyone has an option to discuss and our aim is to try to narrow the differences for a possible deal in November," said a person familiar with Saudi Arabia's plans.

Mr. Bouterfa said Sunday that Iran "poses a specific problem."

Abhishek Deshpande, chief oil analyst at French bank Natixis, said OPEC is under more pressure to reach a deal this time. He said he wasn't expecting a full deal this week, but noted that oil producers are beginning to question whether the Saudi policy of battling for market share will ever restore prices.

"There is still a lot of oil in the system, both in 2016 and 2017," he said. "If OPEC doesn't do something, prices will remain under pressure.

Mr. Bouterfa said the informal gathering could be quickly turned into a formal summit. Others believe that is unlikely, but Mr. Bouterfa said the clock is ticking for a decision.

OPEC members are collectively losing $300 million to $500 million a day because of low prices, he said. Low prices have hurt oil-industry investments, which could lead to oil shortages that cause prices to rise.

"OPEC has no choice but to take a decision," Mr. Bouterfa said. "In Algiers or in Vienna" when the group meets on Nov. 30.

Summer Said contributed to this article.

Write to Benoit Faucon at benoit.faucon@wsj.com, Neanda Salvaterra at neanda.salvaterra@wsj.com and Georgi Kantchev at georgi.kantchev@wsj.com

(END) Dow Jones Newswires

September 25, 2016 20:55 ET (00:55 GMT)