Explore how crude oil is transformed into fuels and petrochemicals through interactive animations.
Start ExploringCrude oil is a naturally occurring fossil fuel composed of hydrocarbons formed over millions of years.
Formed from ancient marine organisms buried under sediment over 300–400 million years ago, transformed by heat and pressure.
A complex mixture of hydrocarbons (alkanes, cycloalkanes, aromatics) plus sulfur, nitrogen, oxygen, and metals.
Refineries separate crude oil into fractions using heat, pressure, and catalysts to produce useful products.
Oil powers ~80% of global transport and is the feedstock for plastics, medicines, and thousands of daily products.
Crude oil is a mixture of hydrocarbon families. Select a type to explore its molecular structure and properties.
Straight-chain saturated hydrocarbons. Carbon atoms linked in a single unbranched line with maximum hydrogen atoms. The backbone of crude oil — from methane (C1) to heavy waxes (C50+).
Higher carbon count = higher boiling point = heavier fraction. C1–C4 are gases; C5–C17 are liquids; C18+ are solids (wax) at room temperature.
Same formula as n-alkanes but with branched carbon skeletons. Branching lowers boiling point and improves octane rating. Isooctane (2,2,4-trimethylpentane) defines the octane-100 reference standard.
Catalytic reforming intentionally converts straight-chain naphtha into isoalkanes and aromatics to boost gasoline octane numbers.
Saturated ring-structured hydrocarbons. Carbon atoms form closed loops — 5-membered cyclopentane or 6-membered cyclohexane rings are most common in crude oil.
Major component of naphtha and kerosene fractions. Naphthenic crude oils (common in Southeast Asia) produce better lubricant base stocks.
Unsaturated ring compounds with delocalized π electrons. The benzene ring (C₆H₆) is the core unit. BTEX group — Benzene, Toluene, Ethylbenzene, Xylene — are key refinery products and petrochemical feedstocks.
High octane number makes aromatics valuable in gasoline blending. Polycyclic aromatics (PAH) in heavy fractions are carcinogenic and must be removed during hydrotreating.
The heaviest fraction. Multiple fused aromatic rings with long alkyl side chains, plus heteroatoms: S, N, O, and metals (Ni, V). Molecular weights can exceed 1,000 g/mol.
Asphaltenes cause fouling in refinery equipment. They become bitumen/asphalt after processing. Heavy crudes like Venezuelan Orinoco or Canadian oil sands are asphaltene-rich.
Click on each product to learn more. Lighter fractions rise to the top; heavier ones sink to the bottom.
Click each step to understand what happens at that stage of the refinery.
Raw crude oil arrives at the refinery via pipelines or tankers. It is stored in large tanks before processing begins. Crude varies in viscosity and sulfur content — "sweet" crude has low sulfur, "sour" crude has high sulfur.
Watch how large hydrocarbon molecules are broken into smaller, more valuable ones. Press Start to begin.