Refinery Yield Slates and Configuration
A refinery doesn't produce a fixed mix of gasoline, diesel and jet fuel from crude oil — it can shift that mix within limits set by its equipment, and that flexibility is what crack spread traders are really pricing.
Prerequisites: Crack Spreads, Crude Oil Benchmarks: WTI, Brent and Dubai
Pour a barrel of crude oil into a refinery and you don't get one product out — you get a whole slate of them: gasoline, diesel, jet fuel, heating oil, residual fuel oil, and more, all from the same barrel, in proportions that depend on the crude's chemistry and the refinery's own equipment. That proportion is the refinery's yield slate, and how far a refiner can shift it — making relatively more diesel and less gasoline, say — is set by its configuration, the specific set of processing units it owns.
A refinery's yield slate is not fixed. Simple refineries are stuck close to what distillation alone produces; complex refineries with cracking and coking units can reshape a barrel toward whichever products are most valuable that month. That flexibility is exactly what crack spread economics reward.
Simple versus complex refineries
The starting point for every refinery is atmospheric distillation: heat crude oil and separate it by boiling point into straight-run fractions — light gases, naphtha, kerosene/jet, diesel, and heavier residues. A simple (topping) refinery stops close to there, so its yield slate is largely dictated by the crude it buys: "light, sweet" crude naturally yields more gasoline- and diesel-range material; "heavy, sour" crude yields more low-value residual.
A complex refinery adds secondary units — a fluid catalytic cracker (FCC) breaks heavy molecules into more gasoline, a hydrocracker yields more diesel/jet, and a coker converts the bottom of the barrel into light products plus solid petroleum coke. These units let a complex refinery shift the same crude toward gasoline or diesel depending on which crack spread is more profitable, and process cheaper, heavier crude a simple refinery couldn't handle.
Worked example
A complex refinery processes 100,000 barrels/day of crude. Its yield slate is 45% gasoline, 40% diesel/jet, 15% residual and coke. If gasoline is trading at a $22/barrel crack over crude and diesel at a $28/barrel crack, while residual only fetches a $4/barrel discount to crude, the refiner's blended margin is roughly: (0.45 × 22) + (0.40 × 28) + (0.15 × -4) = 9.9 + 11.2 − 0.6 = $20.50/barrel, before fixed operating costs. A simple refinery running the same crude but yielding only 20% gasoline, 30% diesel, 50% residual earns: (0.20 × 22) + (0.30 × 28) + (0.50 × -4) = 4.4 + 8.4 − 2.0 = $10.80/barrel — roughly half, because it can't convert the low-value residual fraction into anything better.
What this means in practice
Refining margins hinge on configuration as much as on crude prices. When diesel cracks run far above gasoline cracks (common in winter or during a shortage), complex refiners with hydrocrackers lean output toward diesel and capture that spread, while simple refineries are stuck with whatever distillation gives them. This is why refinery upgrade projects — adding a coker or hydrocracker — are capital decisions worth billions: they buy flexibility to chase whichever crack spread is fattest.
A refinery cannot instantly retune its yield slate to chase a spread — shifting output meaningfully toward diesel or gasoline takes operating changes over days to weeks, and some flexibility (like the diesel-vs-gasoline split from an FCC) is much easier to adjust than others (like total residual output, which is largely fixed by the crude's own chemistry).
Further reading
- EIA, 'Refinery Yield' data series and methodology