Global oil inventories held by developed economies fell further below historical averages in June, reducing the market’s supply cushion as oil demand remains resilient, according to the Organization of the Petroleum Exporting Countries’ (OPEC) August 2026 Monthly Oil Market Report.
Commercial oil stocks in the OECD (Organisation for Economic Co-operation and Development) fell by 26.4 million barrels in June to 2.729 billion barrels, OPEC said. Inventories were 59.6 million barrels below their level a year earlier and 66.5 million barrels below the latest five-year average.
The decline highlights a tightening in the physical oil market even as crude prices weakened in July. OPEC’s reference basket fell $6.76 a barrel from June to an average of $82.99, while Brent averaged $83.97 a barrel.
Stock Draws Strengthen Market Tightness
The fall in inventories was broad enough to reinforce concerns about the amount of oil available to absorb unexpected disruptions in supply.
OPEC’s data show that OECD commercial stocks remained below recent historical benchmarks, leaving inventories at levels that provide a smaller buffer against stronger demand or supply interruptions.
The inventory decline also comes as refinery activity has picked up. Global refinery intake increased by 1.4 million barrels a day in July, with refinery utilization exceeding 78%, according to OPEC. Strong demand for middle distillates, supply disruptions and relatively low product inventories encouraged refiners to increase crude processing.
The combination of lower inventories and stronger refinery activity is particularly significant for refined fuels, where supply conditions have already tightened in some major markets.
Diesel Market Under Pressure
Europe’s diesel market provides one indication of that pressure. The gasoil crack spread against Brent averaged $72.45 a barrel in July, an increase of $27.17 from June and $44.14 from a year earlier, OPEC said. The rise was linked to Russia’s diesel export ban, refinery outages and already-tight supplies, according to the report.
The developments could keep refined-product markets sensitive to further disruptions, particularly as refiners prepare for seasonal demand.
Winter Demand Could Draw More Stocks
OPEC expects heating fuel demand in OECD countries to increase during the northern hemisphere winter.
Demand for heating fuels is projected to rise by about 70,000 barrels a day year-on-year in the fourth quarter of 2026, followed by an increase of about 100,000 barrels a day in the first quarter of 2027.
That seasonal increase could place additional pressure on inventories that are already below their five-year average.
At the same time, OPEC expects global oil demand growth to accelerate in 2027, with consumption forecast to increase by 2.2 million barrels a day, compared with about 580,000 barrels a day in 2026.
Supply Growth Provides Counterweight
The inventory picture is not uniformly bullish for crude prices.
OPEC expects liquids production from non-OPEC countries to increase in both 2026 and 2027, with Brazil, the US, Canada and Argentina among the main sources of additional supply.
That additional production could replenish inventories and offset some of the pressure from stronger demand.
For now, however, the latest stock data point to a market with less inventory protection than in previous years. With stocks below historical averages, stronger winter consumption or an unexpected supply disruption could have a larger effect on prices and refined-product markets than it would in a better-stocked market.
