Iraqi Supply Disruption May Reveal True Constraints of OPEC's Spare Capacity

Iraq’s Oil Output Faces Major Disruptions

Iraq has started curbing its oil production as export routes through the Strait of Hormuz become increasingly restricted. Currently, about 1.5 million barrels per day are reportedly offline, with officials cautioning that this number could climb to 3 million barrels per day if the situation does not improve.

If production losses reach 3 million barrels per day, it would represent one of the most significant sudden supply interruptions in recent history, outside of events like sanctions or armed conflict.

Iraq’s Oil Production and Export Landscape

According to recent OPEC data, Iraq’s crude oil output typically ranges from 4.0 to 4.3 million barrels per day. The country usually exports between 3.2 and 3.4 million barrels daily, with most shipments departing from the southern Basrah terminals. China and India together receive nearly two-thirds of these exports, making Iraq a vital supplier of heavy crude to Asia.

The majority of Iraq’s oil comes from southern fields that supply Basrah. The Rumaila field alone can produce between 1.4 and 1.5 million barrels per day and often exceeds 1.3 million barrels daily. West Qurna 1 delivers around 600,000 barrels per day, with a capacity close to 650,000–670,000. West Qurna 2 is currently producing about 460,000 barrels per day, though expansion plans aim for 750,000–800,000. Zubair’s design allows for roughly 700,000 barrels per day, and the Maysan complex adds another 300,000–350,000 barrels daily.

These key fields collectively drive Iraq’s export capacity. If 3 million barrels per day are shut in, most of the southern export system would be sidelined, removing a substantial portion of medium and heavy sour crude from the global market.

Can OPEC Fill the Gap?

This situation raises a critical question: Is OPEC able to compensate for such a large supply shortfall?

The answer varies depending on how spare capacity is defined. In December of last year, the EIA updated its definitions: “maximum sustainable capacity” is the highest output a producer could achieve within a year under ideal conditions, while “effective capacity” refers to the volume that can be brought online within 90 days and maintained without harming infrastructure.

It’s important to note that the EIA uses the 90-day “effective capacity” as the standard for spare capacity.

So, does OPEC have enough spare capacity to quickly offset a major Iraqi outage?

Based on the 90-day metric, OPEC’s effective spare capacity is generally estimated at 3 to 4 million barrels per day. Nearly all of this is concentrated in Saudi Arabia and the United Arab Emirates. Saudi Arabia can provide about 2 million barrels per day, while the UAE can add 0.8 to 1.0 million barrels daily. Other OPEC members contribute only minor amounts.

Limits of Spare Capacity

If Iraq’s production cuts approach 3 million barrels per day, OPEC would be pushed to the edge of its spare capacity, relying almost entirely on Saudi Arabia and the UAE to ramp up output and ship oil through the same congested Strait of Hormuz. Achieving this would take up to 90 days, as per the EIA’s definition, and mobilizing such volumes is far from immediate.

Additionally, the type of crude matters. Iraq mainly exports medium and heavy sour grades, which are preferred by refineries in China and India. These facilities, which together process about 2.1–2.5 million barrels per day from Iraq, are optimized for heavier crude. Replacing these with lighter grades would affect yields, diesel production, and refining profits—a trend already visible in the tightening price spreads for heavy crude.

Even if upstream production issues are resolved, logistical challenges remain. Most replacement barrels would still need to transit the Strait of Hormuz. Any delays, increased insurance costs, or tanker hesitancy would shift the bottleneck from production to transportation. Having spare capacity in the ground does not guarantee immediate delivery to global markets.

Timing is also crucial. The 90-day window to bring spare capacity online is a long period in a fast-moving market. A sudden loss of 3 million barrels per day would demand an urgent response, leaving little room for a gradual ramp-up.

In summary, while OPEC has spare capacity on paper, a prolonged Iraqi outage of this magnitude would quickly shift the focus from theoretical spare capacity to the practical ability to deliver the right type of oil through functioning shipping lanes. The margin for error would be much slimmer than headline figures suggest.

By Julianne Geiger for Oilprice.com

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