OPEC+ has delayed a review of members’ oil production capacity that will help determine their 2027 output quotas, after the U.S.-Israeli war on Iran disrupted projects intended to expand production across the Middle East and clouded estimates of future supply, two sources familiar with the matter told Reuters.
The review was originally scheduled for completion by the end of September 2026. The deadline has now slipped to mid-November, the sources said, potentially leaving OPEC+ with only a short window to assess the findings before its next group-wide meeting later that month.
The delay highlights how the conflict has complicated one of the oil alliance’s most politically sensitive exercises. Production-capacity estimates are not simply technical measurements. They can determine how much crude individual members are permitted to produce, making changes to the assessment a potential source of tension among countries competing for larger shares of the group’s output.
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OPEC+ includes the Organization of the Petroleum Exporting Countries and allies, including Russia. The alliance ordered the capacity review in late 2025 ahead of setting production baselines for 2027.
At its most recent group-wide meeting in June, OPEC reaffirmed “the importance of completing the maximum sustainable production capacity (MSC) assessment for all (member) countries to be used as reference for 2027 production baselines.”
The review is intended to provide an independent assessment of the maximum amount of oil each member can sustainably produce. But determining that figure has become more difficult as the conflict has delayed projects designed to add new production capacity in parts of the Middle East.
The two sources said not all OPEC+ members had yet submitted the information required for the assessment, without identifying the countries involved.
U.S. petroleum consultant DeGolyer and MacNaughton is conducting the review for OPEC+ members except Russia, Iran and Venezuela, which are under U.S. sanctions, according to sources who spoke to Reuters in late 2025.
The consultancy is now expected to submit its report to OPEC by mid-November, the sources said. That would give the organization time to consider the findings before the next group-wide meeting expected in late November.
Russian Deputy Prime Minister Alexander Novak was reported by state news agency TASS on Friday as saying that OPEC+ countries were continuing to assess their maximum production capacities.
The timing of the review matters because capacity additions that were expected to be completed before the assessment may no longer be available on the original timetable. Projects delayed by the conflict could therefore alter the amount of production capacity that consultants and OPEC+ officials consider sustainable for 2027.
The uncertainty also comes at a time when the oil market is already dealing with disruptions to crude flows and refining operations across the region. For OPEC+, however, the immediate issue is not simply how much oil is unavailable today, but how the conflict changes assumptions about future supply.
A producer that was expected to add substantial capacity could receive a different assessment if its expansion is delayed. Conversely, a member that has successfully completed capacity additions could argue that its production baseline should rise.
Quotas Could Become A New Source of Tension
The capacity assessment is considered necessary because OPEC+ quotas are negotiated against the backdrop of competing interests among members.
Countries with lower assessed capacity could face pressure to accept lower future production allocations, while producers that have expanded their ability to pump crude could seek higher quotas. The review therefore provides a technical basis for what can ultimately become a political negotiation.
The United Arab Emirates had been one of the strongest advocates for increasing its OPEC+ quota to reflect rising production capacity before it left the alliance in May. But Iraq is also seeking a higher quota and has considered leaving OPEC, sources told Reuters in June.
Those disputes explain why the delayed assessment could have consequences beyond the timetable itself. If the review produces materially different estimates of sustainable capacity, it could reopen arguments over how production should be distributed among members.
OPEC+’s challenge is to distinguish between temporary disruptions and lasting changes to productive capacity. A project delayed by war does not necessarily mean the underlying reserves or infrastructure have disappeared. But if construction, equipment deliveries, or other expansion work remains disrupted, the additional barrels may not be available when the new production baselines take effect.
The backdrop has created a moving target for the consultants conducting the assessment and for OPEC+ officials who will eventually use it in quota negotiations. The delay also gives producers additional time to provide updated information as the situation develops. But it could leave the alliance confronting a more complicated decision at its November meeting, when members must consider both the assessment and the wider outlook for oil demand, supply and geopolitical risk.
For the oil market, the significance lies in the potential gap between nominal production capacity and barrels that can actually be brought to market. OPEC+ has traditionally relied on spare capacity as a buffer against supply disruptions, but the value of that buffer depends on how quickly producers can access and sustain those barrels.
The delayed review indicates that even before OPEC+ settles its 2027 quotas, the conflict has already changed the assumptions on which those quotas are being built.