Emergency oil reserves: the refinery sets the pace

Investigation: Emergency fuel reserves, from storage to delivery · Part 4 of 7 · Documents checked on 3 October 2026.

On 9 August 2026, the Donges refinery in western France announced that start-up operations at one unit would continue the following morning. The notice was only a few lines long. It followed an April announcement about units shutting down, then further notices in June and early August describing a gradual restart. Together, they reveal something important about the industrial timetable: a refinery regains capacity in stages. The operator’s notices describe activity, while leaving the throughput actually recovered unspecified. S02 S03 S04 S05

That timetable now features in the G7’s response to oil-market pressures. Its 2 October 2026 statement pairs the release of emergency stocks with plans to coordinate refinery maintenance schedules, avoid simultaneous shutdowns and temporarily raise utilisation where feasible. The commitment concerns the timing of industrial operations as well as the contents of storage tanks. S01

Earlier parts of this investigation examined the reserves themselves, their owners and the journey to filling stations. This instalment moves upstream to processing. What happens when a stock of crude reaches a refinery already running hard, a unit still undergoing maintenance, or a plant with limited capacity to remove sulphur? Assessing what the reserves can deliver requires a closer look at the equipment, and at the statistics used to describe it.

The fuel takes shape across several units

Crude oil contains many different molecules. Heating it and feeding it into a distillation column separates it into fractions according to their boiling ranges. Some streams feed the petrol production chain; others enter kerosene and diesel processing. Heavier fractions have further processing routes and markets. The refinery produces a range of materials, with the mix shaped by its feedstock and configuration. S06

This matters as soon as a reserve is described simply in barrels. Crude in a tank still has to be processed. Oil grades differ in density and sulphur content, among other properties. Heavier crude requires more processing to obtain certain lighter products; sulphurous crude puts demands on the processes that remove that contaminant. Those characteristics help describe the task ahead. A specific product yield would require a fuller crude assay and knowledge of the plant. S07

Chemical processing follows separation. Hydrotreating uses hydrogen and catalysts to remove contaminants, including sulphur compounds. Hydrocracking, where installed, uses hydrogen to help convert heavier fractions into smaller molecules. It can contribute to the production of middle distillates, the family that includes kerosene and diesel. Each finished product must then meet its own specifications. S08 S24

The practical question is therefore where the production chain is being constrained. A distillation unit may have feedstock while a downstream process limits output. Conversely, equipment may be available but waiting for suitable inputs. The relevant diagnosis combines the feed, the processing units and the quality required at the outlet. This follows from the structure of the process; establishing the actual constraint requires evidence about the particular refinery. S06 S07 S24

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Hydrogen is already at work before refuelling

Inside a refinery, hydrogen serves as a chemical reactant, helping to treat and transform hydrocarbons. Some can come from catalytic reforming, a process that also produces petrol blending components. The needs of other units may require additional supplies. Steam reforming of natural gas is one production route for that extra hydrogen. S09 S22 S23

Donges’ Horizon project makes the dependency tangible. TotalEnergies describes two linked installations: a hydrotreater for intermediate feedstocks, known as HDT-VGO, and an SMR hydrogen plant, built and operated by Air Liquide, intended to supply it. The operator’s page says both units entered service in April 2026. It describes their industrial arrangement and relationship; their actual availability on 3 October remains undocumented. S10

Diesel-making capacity therefore depends on more than the volume of oil a site can distil. Hydrogen supply and treatment capacity are part of the production chain. In a scenario where one of those links becomes limiting, additional crude may add to material awaiting processing without immediately increasing shipments of compliant fuel. The effect will depend on the alternative routes and intermediate inventories available. S06 S08 S22

Product specifications give that constraint a concrete boundary. In France, Annex I of the order governing diesel sets a maximum sulphur content of 10 milligrams per kilogram for the fuel it covers. The version examined has been effective since 27 August 2026. A petroleum intermediate must meet the requirements of its intended use before it can be sold as that finished product. The diesel limit cited here should not be transferred to jet fuel. S11

A stock of finished, compliant fuel thus has a particular industrial value: the processing work has already been done. When a treatment unit is the bottleneck, such a stock can temporarily supply the market while production capability is restored. Its usefulness still depends on location and withdrawal arrangements, examined in the previous instalment. Choosing between crude and finished-product reserves means identifying the specific gap that needs to be covered. S06 S11

What a utilisation rate actually measures

Refinery capacity looks straightforward when expressed in barrels per day. Yet the number depends on the reporting convention. The US Energy Information Administration distinguishes barrels per stream day, which assume optimal operation without downtime, from barrels per calendar day, which incorporate usual constraints and an allowance for maintenance. The latter is intended to reflect more realistic operating conditions. S12

That difference matters when estimating how much more can be produced. Applying a maintenance discount to a figure that already includes one can count the same constraint twice. Treating a stream-day rating as a promise of continuous output goes too far in the other direction. A calculation needs to start with the definition of its denominator. S12

The EIA’s weekly report published on 30 September 2026, covering the week ended 25 September, provides a recent example. It reports US gross inputs to distillation of 16.670 million barrels per day, against 18.027 million barrels per day of operable capacity. The published utilisation rate is 92.5%. Gross inputs form the numerator of that measure; crude oil inputs alone appear on a different line of the table. S13 S14

Under the EIA definition, operable capacity also includes some temporarily inactive facilities. The statistic measures activity against an equipment base defined by a reporting convention. The gap to 100% combines situations with different prospects for returning to production. Adding those gaps does not establish a volume of diesel that could be supplied tomorrow. S13

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Regional differences make the national average easier to interpret. The published rate was 95.9% on the Gulf Coast and 85.6% in the Midwest. The two regions have very different-sized refining sectors. Showing both inputs and capacity alongside the percentages preserves that distinction: a high rate in a small region and a similar rate in a large industrial basin imply very different volumes. S14

Estimating additional supply would require a further layer of information. Which units are available? What feeds can they handle? Which extra products could they deliver? The US series helps explain how to read a utilisation indicator. Applying it directly to France, or turning its apparent headroom into exportable diesel cargoes, would require evidence absent from this table. S07 S13 S14

Donges’ notices trace a phased restart

Donges’ bulletins offer a more granular view of operations than a simple “open” or “closed” label. On 23 April, the operator said shutdown manoeuvres had begun that week and were scheduled to continue through 17 May. That end date applied to the operations described in the notice. It was not the completion date for the entire turnaround. S02

A notice dated 23 June described work gradually coming to an end and equipment returning to service in stages. On 16 July, a bulletin announced the completion of work while describing a gradual restart; the headline of the 24 July notice repeated that completion announcement. On 3 August, the company said the restart was continuing. On 9 August, it announced further start-up manoeuvres at one unit for the following day. These documents establish a sequence of statements about industrial steps. They provide neither a cumulative production loss nor evidence that the whole refinery was continuously shut between April and August. S03 S29 S27 S04 S05

The updated search also found two September notices. On 5 September, the operator reported an equipment malfunction at a major unit, flaring and a fire at the base of the flares that the site’s response teams brought under control. On 6 September, it announced start-up operations at a unit that afternoon. Neither notice identifies the unit or quantifies lost output; their consecutive dates alone cannot establish a link between the malfunction and restart. These announcements complement the four selected milestones in the chart below. S28 S26

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Start-up deserves its own place in the analysis. In an alert issued in August 2017, following Hurricane Harvey, the US Chemical Safety Board set out the precautions required: inspect equipment, follow established procedures and pay particular attention to the many tasks occurring simultaneously. That historical document explains a general safety issue. It makes no assessment of Donges’ operations in 2026. S16

The economic implication can easily be overlooked. Where restarting involves several stages, the date of the first manoeuvre cannot establish when all saleable output returns. Quantifying the recovery would require actual throughputs, the products obtained and their compliance with specifications. A notice provides a milestone; recovering a volume is something that must be measured. S06 S16

This is the rationale behind the G7’s proposed maintenance coordination. Where work schedules have flexibility, staggering them could reduce the overlap in unavailable capacity. Feasibility depends on the constraints and safety requirements of each site. Postponing maintenance may shift exposure to a later date, so the assessment must cover the whole period, including when that work eventually takes place. This describes the intended mechanism, rather than a measured result of the 2 October decisions. S01 S16

As of 3 October 2026, the documents assembled here do not provide daily output at Donges or operating rates for each unit. The chronology preserves that limitation. The notices help document a phased restart; they are not a live operational dashboard for the refinery.

Prices create incentives within an industrial boundary

Some configurations do allow production to rise. On 25 March 2026, the French government announced an additional 12,000 tonnes of jet fuel and 15,000 tonnes of diesel per month at Gravenchon. Those were announced targets. We found no series in the assembled documents that would verify their delivery or duration. The case nevertheless points to the need to examine local scope for higher output rather than assume that every refinery is equally inflexible. S17

Refineries have some operating choices. These include feedstock selection and, in processes such as hydrocracking, the ability to adjust the balance between product families. The outcome depends on equipment and operating conditions. A proposed increase at one site remains specific to that site; it supplies no coefficient that can safely be applied to the entire refining system. S07 S08

The commercial signal also needs to be interpreted carefully. TotalEnergies’ European Refining Margin Marker uses public market prices, a crude basket, product yields and representative variable costs. It tracks a market environment. Establishing a plant’s profit would require its actual volumes, its own costs and its other expenses. An attractive reference margin can create an incentive to produce more while an unavailable unit still prevents the increase. S20

Globally, the IEA estimates August 2026 refinery throughput at 81.4 million barrels per day. That was 0.96 million higher than July, yet 4.2 million below August 2025. A monthly recovery can therefore coexist with a substantial year-on-year shortfall. These are aggregate estimates, separate from the condition of individual plants. S15

The European assessment adds an important counterpoint. On 29 September, the Commission’s Oil Coordination Group described EU supply as still stable, despite high diesel and jet-fuel prices. It also said European refineries were operating close to maximum capacity. In that assessment, pressure showed up both in the cost of products and in the limited room to make more. The dated, Union-wide statement does not describe conditions at every filling station. On 2 October, the Commission again described EU diesel supply as stable for the time being, with prices still high. That update retains its Union-wide scope and cannot guarantee availability at each French station. S21 S25

France’s recovery still includes flows in both directions

French statistics require several time horizons to be kept in view. According to the 2026 edition of the SDES energy statistics, domestic refined-product output, net of refineries’ own consumption, reached 555 TWh in 2025, up 3.6% from 2024. These provisional figures cover mainland France and its five overseas departments. They describe the previous year, before the industrial sequence examined here. S18

Trade figures show substantial flows in both directions. For 2025, SDES reports 34.5 million tonnes of oil equivalent in imports and 17.5 million in exports, leaving net imports of 17.0 million. Tonnes of oil equivalent measure energy. The figures combine different refined products; they are neither tonnes of diesel nor barrels held in emergency storage. S18

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The aggregate net import balance fell from its 2021 level, as reported imports declined and exports increased. The trade balance therefore improved over that period. The aggregate is still too broad to establish the availability of a particular fuel at a given time. Exporting one product can improve the overall balance while a different specification still has to be imported. Measuring that requirement means going below the aggregate to individual products. S18 S19

The annual nature of this balance matters too. A year’s production tells us about activity and trade, but very little about whether a particular unit is available on a particular day. Emergency reserves operate in precisely that gap between a balance across the year and deliveries required within a short window. The national energy balance, operating data and inventories consequently need to remain separate measures. S12 S14 S19

Match the reserve to the constraint

The question for an emergency reserve can now be framed more precisely: what work still has to be done before the required product can be delivered?

Consider an available refinery whose feedstock supply has been interrupted. Compatible crude from storage can feed its units. The impact depends on its ability to process that grade and produce the mix of fuels required. In this case, the reserve directly addresses a missing raw material. S06 S07

Now consider a different constraint: feedstock is available, but a unit needed to make compliant fuel remains limited. Releasing already-refined product may support deliveries while the plant recovers its processing capability. The intervention should be assessed by the product, the quantity and the period it can cover. This is a conditional explanation, with no invented estimate of how long a French refinery’s shortfall could be covered. S06 S11 S24

Where a refining system is already operating close to what its configuration permits, additional supply might come from another site, an altered production programme or finished-product inventories. Transport and product quality then need to be checked. The flexibility described in refining processes and the Gravenchon announcement warrant examining those options. Operating-rate assessments caution against assuming how large their contribution could be. S08 S17 S21

The G7 statement addresses both time horizons: stock releases intended to act quickly, including a substantial frontloaded diesel component within the first twenty days, and work on refinery schedules. The 100 million barrels announced over four months, with releases to begin immediately on 2 October, form part of implementing the March commitments, taking account of those already fulfilled. Their contribution to supply will depend on the products released and, for crude, the processing capacity actually available. S01

Refining gives an emergency reserve a dimension that disappears from aggregate volumes: the work still required, and the time needed to complete it. As a constraint moves closer to the finished product, the composition of the backup stock becomes increasingly important. Once the right product has been identified, the next question is who can obtain it, under which sale, loan or return terms. That is the subject of part five.

Further reading

• Part 1: the journey from storage to diesel examines the product mix and announced release schedules.
• Part 2: who owns France’s emergency oil? follows ownership, funding and release rights.
• Part 3: the distance to the pump examines depots, transport and filling-station tanks.
• SPR: understanding emergency oil reserves connects stored products with release constraints.
• Read the oil market puts stocks and refining in the context of price formation.

Sources

1. G7 / Conseil européen : G7 Leaders’ Statement on global energy security and market stability. 2026-10-02. Measures announced on 2 October 2026.
2. TotalEnergies Donges : Grand Arrêt 2026 : manœuvres d’arrêt d’unités. 2026-04-23. Shutdown manoeuvres underway during publication week, scheduled through 17 May 2026.
3. TotalEnergies Donges : Redémarrage progressif des unités de la raffinerie. 2026-06-23. Bulletin dated 23 June 2026; an internal reference to 20 June.
4. TotalEnergies Donges : Le redémarrage des unités de la raffinerie se poursuit. 2026-08-03. Situation described on 3 August 2026.
5. TotalEnergies Donges : Raffinerie de Donges : redémarrage d’une unité. 2026-08-09. Start-up manoeuvres scheduled for Monday 10 August 2026.
6. U.S. Energy Information Administration : Refining crude oil: the refining process. General technical explanation, consulted 3 October 2026.
7. U.S. Energy Information Administration : Refining crude oil: inputs and outputs. Technical explanation; page updated 20 June 2024.
8. Pennsylvania State University / Semih Eser : Catalytic Hydrocracking, FSC 432. Process fundamentals; update date not established.
9. U.S. Energy Information Administration : Hydrogen explained: production of hydrogen. Hydrogen-production fundamentals.
10. TotalEnergies Donges : Le projet Horizon. Project description, consulted 3 October 2026.
11. Légifrance : Arrêté du 23 décembre 1999, annexe I : caractéristiques du gazole. Version effective from 27 August 2026, amended by the order of 22 July 2026.
12. U.S. Energy Information Administration : Glossary: barrels per calendar day / barrels per stream day. Definitions consulted 3 October 2026.
13. U.S. Energy Information Administration : Glossary: operable capacity and utilization. Definitions consulted 3 October 2026.
14. U.S. Energy Information Administration : Weekly Petroleum Status Report, Table 2. 2026-09-30. Week ended 25 September 2026; United States and five PADD regions.
15. International Energy Agency : Oil Market Report, September 2026: public highlights. 2026-09-11. August 2026 estimates, compared with July 2026 and August 2025.
16. U.S. Chemical Safety and Hazard Investigation Board : Safety precautions during startups following Hurricane Harvey. 2017-08-27. Historical alert from August 2017; general start-up safety principles.
17. Gouvernement français : Compte rendu du Conseil des ministres du 25 mars 2026. 2026-03-25. Measures and additional production announced in March 2026.
18. SDES : Chiffres clés de l’énergie, édition 2026 : pétrole. 2026-09-30. 2021 and 2025 data; 2025 provisional. France including the five overseas departments. Publication notice for the 2026 edition.
19. SDES : Chiffres clés de l’énergie, édition 2026 : bilan énergétique physique 2025. 2026-09-30. 2025 physical energy balance, unadjusted data; TWh. Publication notice for the 2026 edition.
20. TotalEnergies : Main indicators: European Refining Margin Marker. ERM definition introduced in 2024; current page consulted 3 October 2026.
21. Commission européenne, DG Énergie : Oil Coordination Group: Continued concern about prices while supply remains stable. 2026-09-29. Assessment on 29 September 2026, European Union.
22. Pennsylvania State University / Semih Eser : Hydrogen Production, FSC 432. Technical principles; update date not established.
23. Pennsylvania State University / Semih Eser : Catalytic Reformer, FSC 432. Technical explanation; update date not established.
24. Pennsylvania State University / Semih Eser : FSC 432, Petroleum Refining: sections Catalytic Hydrotreatment and finishing. Course technical fundamentals.
25. Commission européenne, DG Énergie : Energy Union Task Force: diesel supplies and prices in Europe. 2026-10-02. European Union aggregate assessment on 2 October 2026.
26. TotalEnergies Donges : Redémarrage d’une unité de production de la raffinerie. 2026-09-06. Operations announced for the afternoon of 6 September 2026; operator statement.
27. TotalEnergies Donges : Fin des travaux du Grand Arrêt 2026 : le redémarrage des unités de la raffinerie se poursuit. 2026-07-24. Completion of work announced in the title, with restart continuing; operator statement.
28. TotalEnergies Donges : Émergences aux torches. 2026-09-05. Malfunction and a fire reported as brought under control on 5 September 2026; operator statement.
29. TotalEnergies Donges : Redémarrage des unités de la raffinerie. 2026-07-16. Completion of work and a progressive restart announced on 16 July 2026; operator statement.

Scope and method

This investigation uses public documents, without site visits or interviews. Donges’ bulletins are operator statements; Gravenchon’s additional volumes are government announcements; IEA figures are estimates; France’s 2025 data are provisional. Conditional examples explain mechanisms. Missing daily output has not been reconstructed.

Two source cautions. Donges’ 23 June bulletin uses the future tense for 20 June; we infer no confirmed commissioning date from it. The SDES page describes a 32% fall in net imports, although its stated levels, 33.2 and 17.0 Mtoe, imply about 48.8% when calculated from those rounded levels. The chart preserves the reported levels, with recalculated net balances, and avoids the inconsistent percentage. The same SDES administration’s 2025 physical energy balance cross-checks the recent net figure at 197.46 TWh. This remains an internal consistency check. S03 S18 S19

The references above link directly to the sources. The published data are available to download: EIA inputs and capacity, four selected Donges notices, French refined-product trade and the net-import bridge. The chronology selects publications; it is not an exhaustive operational log.