Oil reserves: the journey from storage to diesel

Emergency fuel reserves and the delivery test · Investigation, part 1 of 7 · 3 October 2026

The G7 has announced the release of 100 million barrels over four months, with an early push to supply diesel. Understanding how much relief those barrels can provide starts with what is in storage. Crude oil, diesel and jet fuel sit at different points in the industrial process. The contents of a reserve help determine how quickly it can respond. S01

The US timetable makes that tangible. On 29 September, the Department of Energy invited proposals for an exchange of up to 40 million barrels of crude oil from the Strategic Petroleum Reserve. Bids are due on 6 October at 11 a.m. US Central Time, as specified in the announcement. Deliveries are scheduled for November and December. Several steps still separate the announcement from usable fuel. S02

Three days later, the G7 set another deadline: a substantial diesel release within the first twenty days of a four-month operation. Its commitment of 100 million barrels is framed as the implementation of pledges made in March. The statement leaves the split between crude and refined products, and individual country contributions, unspecified. Adding the headline number to the 400 million barrels agreed through the International Energy Agency in March would treat an operation described as implementation as an entirely new commitment. S01 S03

That brings this investigation to a basic physical question: what form is the oil in while it waits to be released? A tank of crude holds feedstock that still requires processing. Stored diesel has already passed through most of that industrial transformation. The difference determines which facilities a release will still need. S09 S10

Two kinds of insurance in the tank

Crude oil is a mixture. A refinery separates its components, converts some of them and treats the resulting streams to produce fuels suited to particular uses. Gasoline for spark-ignition engines, diesel for diesel engines and kerosene for aircraft have distinct requirements. The plant produces several families of products at once. S09 S10

Releasing crude adds material at the upstream end of that process. It requires transportation, a refinery equipped to process the oil and available capacity in the relevant units. The resulting products then move through storage and distribution. Choosing to hold crude leaves that industrial journey to be completed after the reserve is tapped. S04 S06 S10

Refined-product stocks join the chain further downstream. Stored diesel can move into distribution without going through the main crude-refining process again. It must still meet the requirements of its intended use; any necessary blending or adjustment and the transport itself remain to be arranged. The IEA specifically identifies the value of product stocks when refining capacity is disrupted. S04 S08 S15

The advantage depends on where the interruption occurs. Crude can help keep an operating refinery running when its regular feedstock fails to arrive. If the refinery itself is unavailable, stored fuel can bypass that stage. A terminal cut off from its distribution network presents a different problem again. Equal volumes of oil can provide quite different forms of protection.

Refining determines which fuel becomes available

US data put numbers on the constraint. For calendar year 2025, the Energy Information Administration’s refinery-yield series reports 45.9% for finished motor gasoline, 30.0% for distillate fuel oil and 11.0% for kerosene-type jet fuel. The version of the table consulted was released on 30 September 2026. It describes the US refining fleet across a whole year. S07

The monthly series available on 3 October runs through July 2026: gasoline 43.8%, distillates 30.0% and jet fuel 12.0%. The chart below retains the latest complete year, 2025, as an annual reference less affected by seasonal variation. S18

“Distillate fuel oil” needs careful interpretation: it includes diesel fuels as well as fuel oils used for heating and other purposes. Calling the category road diesel would narrow its scope incorrectly. Yield relates product volumes to crude oil, hydrogen, other hydrocarbons and net unfinished-oil inputs, with specific adjustments for gasoline and distillates. Refining also creates a volume gain: subtracting these three figures from 100% would not produce a valid “other” category. The series describes the output of a refining fleet. S08

The figures show why processing crude supplies several markets at once. Our analysis of US diesel and export demand follows those separate markets. They explain the mechanism; multiplying the 40 million barrels in the US solicitation by the distillate yield would produce a misleading estimate of future diesel supply. That calculation would require the grades awarded, the receiving refineries, their operating plans and the other inputs they will process.

Refiners have some room to change their output. EIA describes product volumes varying with market conditions and operating decisions. That flexibility exists within a physical system of separation, conversion, treatment and blending. The G7 statement acknowledges the industrial constraint by calling for coordinated maintenance and higher utilisation where feasible. S09 S10 S01

The economic transmission follows the process. When the binding constraint is the capacity to make diesel, extra crude may offer limited immediate relief in that product market. When refineries lack feedstock, the same intervention can support several fuel streams. Those are alternative mechanisms, whose actual importance has to be established from operating conditions.

The case for America’s crude reserve

The US Strategic Petroleum Reserve, or SPR, stores crude oil in salt caverns at four federal sites in Texas and Louisiana. That description applies to the SPR itself, rather than all petroleum stocks held in the United States. S05 S06

DOE explains the choice in terms of large-scale storage economics, crude oil’s greater stability over time and the country’s ability to refine it. Finished products require their quality and changing commercial specifications to be managed. These are the reasons given by the public operator of the reserve. S05

Judging a crude reserve solely by the time it takes to fill a truck’s fuel tank would miss part of its purpose. It preserves feedstock capable of supplying several markets. That flexibility has value when the fuel most likely to be scarce in the next emergency is still unknown, provided the necessary processing facilities remain available.

Holding a finished fuel makes the opposite trade-off. Much of the processing has already been done, but the stored product is more closely tied to a particular use. Aviation kerosene and motor gasoline have different specifications. Reserve design prepares for a combination of needs and disruptions, carrying both maintenance costs and industrial dependencies. S08 S04

SAGESS holds a substantial share as finished products

SAGESS, the French Société anonyme de gestion de stocks de sécurité, responsible for building and maintaining a large part of France’s emergency oil stocks, illustrates a different approach. Its July 2025 brochure describes 13.2 million metric tonnes at the end of 2024. Gasoil accounted for 49.8%, crude oil for 30.6%, with the balance divided between gasoline, jet fuel and heating oil. This is SAGESS’s portfolio, rather than France’s entire national stockholding system. S11

In that snapshot, refined products made up 69.4% of SAGESS’s holdings, calculated by adding the four relevant categories. A large share of the portfolio had therefore already passed through the principal industrial transformation. Release arrangements and delivery would still be needed to turn that downstream position into supplies reaching customers.

The date matters as much as the composition. SAGESS’s 2025 annual report, published on 11 June 2026, reports a rounded total of 13.2 million metric tonnes, including loans, at 31 December 2025. That updates the overall quantity. Combining it with the 2024 percentages would invent a 2025 breakdown, so the composition shown here remains explicitly dated to 2024. S12 S13

Nor can either year-end figure serve as a gauge for 3 October 2026. Establishing current availability by product requires an updated inventory that distinguishes oil physically held, quantities on loan and commitments already allocated. The public documents assembled for this first instalment do not support a complete reconstruction of that position.

SAGESS also describes storage at third-party facilities, with requirements for quantity, quality and inspection. These stocks remain part of an operating system that has to be maintained. Knowing that a tank is full tells us relatively little about the time needed to supply a particular customer. S12 S15

“Days of cover” needs a denominator

The units used to describe emergency stocks introduce another source of confusion. A barrel measures volume; a tonne measures mass. Converting between them requires an appropriate density assumption. Regulatory statistics apply their own equivalence rules. Refinery yields, measured in volumes, answer a different question again. S08 S12

SAGESS’s annual report provides a useful example. In its calculation of finished-product-equivalent stocks, where crude substitution is permitted, one tonne of crude counts as 0.8 tonnes. This is a coefficient used to account for the obligation. It is neither a refinery’s diesel yield nor a direct conversion from stored crude into available gasoil. S12

The IEA requires its net-importing members to hold at least 90 days of net imports, in crude, products or a combination. S04

At EU level, the Commission describes an obligation based on the higher of 90 days of net imports or 61 days of consumption. Days calculated against imports therefore compare stocks with a different flow from total consumption. The resulting measure establishes regulatory cover. Maintaining individual deliveries also depends on the product mix and access to the stocks; the EU framework includes availability requirements and emergency procedures for that reason. S16 S17

Days of cover can be useful for comparing holdings with the obligation they are intended to meet. Answering a haulier who needs diesel next week requires the additional detail of product, location and timing.

From a decision to an actual lifting

The US solicitation illustrates how much a release headline can contain. As this article is published, the 6 October bidding deadline is still ahead. Deliveries are planned for November and December. Forty million barrels is the maximum offered for exchange; the amount eventually awarded and withdrawn will have to be established from the results and operational reporting. S02

The solicitation specifies two ceilings of 20 million barrels, for November and December respectively. It does not commit DOE to awarding contracts. Available capacity may be reduced by earlier operations; companies must arrange terminal deliveries. Withdrawal capacity therefore enters the contract before the oil even travels to a refinery. S19

The G7 timetable, meanwhile, describes a collective operation intended to start immediately, with an early emphasis on diesel. The two documents alone do not establish the precise accounting relationship between the US 40-million-barrel offer and the G7’s 100-million-barrel commitment. Placing the schedules alongside each other reveals their different horizons. Adding the quantities, or assigning one entirely inside the other, would require further documentation. S01 S02

Sources: G7 and DOE. Announced schedules, without adding the volumes or assuming contract awards.

A withdrawal from a reserve must then be distinguished from supply reaching a fuel market. Crude lifted under a contract may still need refining. A finished product may be available at a terminal but awaiting transportation. And the quantity released under an emergency programme does not automatically measure the net increase in deliveries to consumers: it may replace an ordinary cargo that failed to arrive. Filling such a gap is precisely what emergency stocks are designed to do. S04 S10

Relief can therefore take the form of a shortage avoided. Measuring it requires reserve withdrawals to be considered alongside normal arrivals, processing and demand. The announced aggregate leaves those relationships unresolved.

The bottleneck determines the response

Stock managers acknowledge the logistics constraint. At a French National Assembly hearing on 8 April 2026, SAGESS chairman François Boussagol explained that access to underground stocks depends in part on pipeline throughput. He described stocks at terminals and refineries as easier to mobilise. The public record gives his assessment of the logistical constraint, without independently measured delivery times for each location. S14

That observation gives the first finding of this investigation its practical meaning: what is held in reserve determines the journey still to be completed. Crude requires processing. A finished fuel reduces that dependency while retaining requirements for quality control and transport. The product mix supplies information that disappears inside a single barrel total.

The strongest case for large crude holdings remains relevant. With refineries and transport links operating, they can support a diverse range of products and preserve options. The G7’s emphasis on diesel points to a need further downstream. The two approaches can complement each other. Their effectiveness will depend on how well the released product matches the constraint encountered.

The next documents needed to assess execution are therefore specific: a breakdown by country and product, the quantities allocated, and a schedule of volumes actually withdrawn and delivered. The official statements reviewed on 3 October contain no collective record of diesel delivered to end users under the previous day’s announcement. S01 S02

The next instalment will trace those products back to their owners and the contracts governing their release. Establishing usable relief requires knowing who can authorise a withdrawal, who receives the fuel and what must eventually be returned.

Further reading

• Part 4: the refinery sets the pace follows processing units, hydrogen and maintenance schedules.
• Part 3: the distance to the pump follows depots, transport and the rebuilding of local inventories.
• Part 2: who owns France’s emergency oil? follows ownership, financing and release rights.
• Strategic oil reserves buy time follows exchange contracts and repayments.
• Yanbu and the constraints on an oil route examines physical delivery.
• Read the oil market connects stocks, refining and prices.

Sources

1. G7 / Présidence française : G7 Leaders’ Statement on global energy security and market stability. 2026-10-02.
2. U.S. Department of Energy : The United States Energy Department Continues Execution of Strategic Reserve Release Commitments. 2026-09-29.
3. International Energy Agency : IEA member countries to carry out largest ever oil stock release. 2026-03-11.
4. International Energy Agency : Oil security and emergency response. Undated page, reviewed 3 October 2026.
5. U.S. Department of Energy : SPR FAQs. Undated page, reviewed 3 October 2026.
6. U.S. Department of Energy : SPR Quick Facts. Undated page, reviewed 3 October 2026.
7. U.S. Energy Information Administration : U.S. Refinery Yield. 2026-09-30.
8. U.S. Energy Information Administration : Table Definitions, Sources, and Explanatory Notes – Refinery yield. Undated page, reviewed 3 October 2026.
9. U.S. Energy Information Administration : Refining crude oil. Undated page, reviewed 3 October 2026.
10. U.S. Energy Information Administration : Refining crude oil – the refining process. Undated page, reviewed 3 October 2026.
11. SAGESS : Corporate brochure 2025. 2025-09-03.
12. SAGESS : 2025 Financial Report. 2026-06-11.
13. SAGESS : 2025 Financial Report – page de publication. 2026-06-11.
14. Assemblée nationale : Audition de François Boussagol, président de la SAGESS. Undated page, reviewed 3 October 2026.
15. SAGESS : Stocker. Undated page, reviewed 3 October 2026.
16. Commission européenne, DG Énergie : Security of oil supply. Undated page, reviewed 3 October 2026.
17. EUR-Lex / Publications Office : Council Directive 2009/119/EC, consolidated text: Articles 3, 5 and 20. 2020-01-01.
18. EIA : U.S. Refinery Yield, monthly series. 2026-09-30.
19. DOE / SPR : Request for Proposal DE-RP96-26PO00006, B-1 and F-1. 2026-09-29.

Scope and method

Public documents reviewed on 3 October 2026. Announcements retain their status as commitments; inventories keep their reference dates. SAGESS figures and DOE’s explanations are attributed to their authors. Parliamentary testimony gives the manager’s logistical assessment. EIA yields use volumes; SAGESS composition uses mass. No conversion between the two measures or projection onto announced releases is made. The regulatory coefficient of 0.8 is separate from refinery yields. No interviews or physical stock inspections were conducted. The cited documents do not reconstruct a collective deployable inventory by product for October 2026.