Oil Refineries: How They Work, and the Giants

Refineries turn crude into the barrel's real products — gasoline, diesel, jet — and their capacity is the hidden bottleneck behind pump prices. US plants are currently running at 96.2% of capacity (EIA, week ending 2026-08-07). Below: the process in brief, the world's largest plants, and the live refining margin.

The World's Largest Refineries

RefineryCountry≈CapacityNotes
Jamnagar (Reliance) India ≈1.24 Mb/d The world's largest — an export machine on the Gujarat coast
Ulsan (SK Energy) South Korea ≈0.84 Mb/d
Paraguana (PDVSA) Venezuela ≈0.94 Mb/d nameplate Operating far below capacity for years
Ruwais (ADNOC) UAE ≈0.82 Mb/d Major expansion underway
Yeosu (GS Caltex) South Korea ≈0.80 Mb/d
Onsan (S-Oil) South Korea ≈0.67 Mb/d
Port Arthur (Motiva) United States ≈0.63 Mb/d Largest in North America; Saudi Aramco-owned
Dangote Nigeria ≈0.65 Mb/d Started 2024 — Africa's largest, reshaping Atlantic gasoline flows
Galveston Bay (Marathon) United States ≈0.59 Mb/d
Baytown (ExxonMobil) United States ≈0.56 Mb/d Oldest of the US giants, opened 1919

Hand-curated from operator disclosures, approximate nameplate capacity. Refining economics live: the crack spread · weekly utilization on fundamentals · what a barrel yields.

Refinery FAQ

How does an oil refinery work?

Three core steps: distillation heats crude (~350–400°C) in a tower where fractions condense at different heights — gases at top, gasoline-range naphtha, then kerosene, diesel, and heavy residue at the bottom; conversion units (catalytic crackers, hydrocrackers, cokers) break the low-value heavy fractions into more gasoline and diesel; and treating/blending removes sulfur and mixes final specification fuels. Complexity is the key economics: simple refineries can only skim light products, while complex ones profitably run cheap heavy sour crude.

What is US refinery utilization right now?

US refineries ran at 96.2% of capacity in the latest EIA week (ending 2026-08-07). Utilization above ~93% signals a tight product market; spring and fall maintenance ("turnaround") seasons typically pull it into the 80s.

What is the largest oil refinery in the world?

The Reliance complex at Jamnagar, India — about 1.24 million barrels per day across its two refineries, built primarily to export fuels to the West. The largest in the US is Motiva Port Arthur, Texas (~630,000 b/d), owned by Saudi Aramco.

Why haven't new refineries been built in the US?

No large greenfield US refinery has been built since 1977 — permitting, community opposition, and the prospect of declining gasoline demand make a multi-billion, 40-year asset hard to justify. Instead, existing sites expanded massively (capacity grew for decades without "new" refineries), and several have recently converted to renewable diesel production.