Crude quality matters

Different types of oil, the refineries that process them, and how the oil flows. A complete reference guide explaining why not all crude oil is created equal — and why that shapes everything from refinery investment to geopolitics.

Named crude streams

200–300

Global refining capacity

~102M [IEA]

World's largest refinery

Jamnagar 1.4M bpd

Highest complexity (NCI)

21.1

Glossary

Key terms you'll see throughout this guide

The oil industry speaks its own language. Here's every term and acronym defined the first time it appears, so nothing trips you up.

Crude stream

A specific, named flow of crude oil from a particular producing field, region, or pipeline blend point. Each stream has a relatively consistent (but slightly varying) set of chemical properties. Think of it like a wine appellation — "Bonny Light" is a stream from Nigeria, "WTI Midland" is a stream from the Permian Basin in Texas. There are 200–300 actively traded named streams globally, but the total universe including obscure and intermittent grades is closer to 700+. New streams are created when pipelines connect new fields, and old ones retire as fields decline.

API gravity

A density scale created by the American Petroleum Institute (API). Formula: API = (141.5 ÷ specific gravity at 60°F) − 131.5. It's an inverse scale — higher numbers mean lighter oil. Water = 10 API. Light crude is above 31 API, medium is 22–31, heavy is below 22. EIA reference.

Sweet / sour

Refers to sulfur content. Sweet = below 0.5% sulfur by weight. Sour = above 0.5%. The terms literally come from the old practice of tasting or smelling the oil. Sulfur is corrosive to refinery equipment, environmentally regulated in finished fuels, and expensive to remove via hydrotreating and hydrodesulfurization (HDS) units.

BPD (barrels per day)

The standard unit for measuring oil production, refining capacity, and trade flows. One barrel = 42 U.S. gallons ≈ 159 liters. "K bpd" = thousands of barrels per day. "M bpd" = millions. Global production in 2025 is roughly 106 million bpd.

NCI (Nelson Complexity Index)

A numerical score that measures how much secondary conversion equipment a refinery has relative to its basic distillation capacity. Invented by Wilbur L. Nelson in the 1960s for the Oil & Gas Journal. A simple "topping" refinery that only distills = NCI 1. Each additional unit (cracker, coker, hydrotreater) adds to the score. Higher NCI = can process worse-quality crude into better products. U.S. average: ~11. Europe average: ~6.5. World record: Jamnagar at 21.1.

Assay

A detailed laboratory analysis of a specific crude oil cargo or stream. Measures dozens of properties including API gravity, sulfur, TAN, metals, nitrogen, pour point, viscosity, and the full distillation yield curve (what fractions come out at each boiling temperature). Every cargo gets an assay before the refinery decides how to process it. Commercial assay databases (Crude Monitor, Haverly) store hundreds of these. Intertek reference.

TAN (total acid number)

Measures naphthenic acid concentration in milligrams of potassium hydroxide (KOH) needed to neutralize 1 gram of oil (ASTM D664 method). High-TAN crudes (above ~0.5 mg KOH/g) corrode carbon steel piping at high temperatures. Refineries need stainless/alloy upgrades or must blend high-TAN with low-TAN barrels. These "opportunity crudes" trade at steep discounts.

Differential (diff)

The price of a specific crude stream expressed relative to a benchmark (usually Brent, WTI, or Dubai/Oman). Example: "Basrah Medium at Brent minus $4.50" means the crude costs $4.50/barrel less than Brent. Differentials fluctuate based on supply/demand, refinery appetite, and logistics.

FCC (fluid catalytic cracker)

A refinery unit that uses heat and a powdered catalyst to break ("crack") heavy gas oil molecules into smaller, more valuable ones — gasoline, diesel, petrochemical feedstocks. The defining unit of a "complex" refinery.

Coker (delayed coker)

A refinery unit that thermally breaks the very heaviest residuum (the "bottom of the barrel") at extreme temperatures into lighter liquids and solid petroleum coke (petcoke). The defining unit of a "deep conversion" refinery. EIA reference.

OSP (official selling price)

The price set monthly by national oil companies (like Saudi Aramco, ADNOC, KPC) for their crude exports. Expressed as a differential to a benchmark (e.g., "Arab Light OSP = Oman/Dubai + $1.20 for Asian buyers"). Refiners use OSPs to plan purchases.

Diluent

A lighter hydrocarbon (usually condensate or naphtha) mixed with extra-heavy crude (like Canadian bitumen or Venezuelan Orinoco crude) to make it thin enough to flow through pipelines. Without diluent, these crudes are too thick to transport.

LP (linear programming)

The mathematical optimization software that refinery planning teams use to determine the optimal mix of crude purchases, blending ratios, and unit operating conditions to maximize profit given their equipment constraints, product demand, and available crude prices.

Section 01

How crude oil is classified

Every barrel is defined by two primary axes: density (API gravity) and sulfur content (sweetness). But there are also crucial secondary properties — TAN, metals, pour point, viscosity, nitrogen — that can make or break a refinery's economics.

Primary axis 1: API gravity (weight)

8 API (bitumen)22 — heavy/medium31 — medium/light50+ (condensate)

Primary axis 2: Sulfur content (sweetness)

0% (ultra-sweet)0.5% — sweet/sour line1.5%5%+ (very sour)

Light sweet Light sour Medium sour Heavy sour

Hover any bubble for exact specs. Dashed lines = sweet/sour boundary (0.5% S) and light/heavy boundary (31 API). Source: EIA crude quality data.

Secondary properties (the ones rookies miss)

API and sulfur get you in the door, but these six properties determine whether a specific cargo actually works for a specific refinery. Sources: Penn State FSC 432, Engineering Toolbox ASTM standards, AFPM Q&A.

TAN (total acid number)

Typical range: 0.01–3.0 mg KOH/g. Above ~0.5 = corrosion risk. Measured via ASTM D664 potentiometric titration. High-TAN crudes corrode carbon steel at temperatures above 220°C (430°F), particularly in vacuum distillation columns and transfer lines. Refineries without alloy-upgraded metallurgy must blend high-TAN down or avoid it entirely.

Metal content (vanadium & nickel)

Range: few ppm to 1,000+ ppm. Concentrate in the heaviest fractions. Vanadium causes refractory damage in furnaces. Both metals poison FCC and hydrotreating catalysts by accumulating on catalyst surfaces, reducing activity. Heavy Venezuelan/Middle Eastern crudes are especially metal-rich. Measured via EPA Method 3040 or ASTM D5185.

Pour point

Temperature below which crude stops flowing. Waxy crudes from West Africa (Bonny Light: pour point ~5°C / 41°F) and SE Asia can solidify in pipelines and tanker holds if they cool down. Requires heated storage, heated pipelines, or pour-point depressant additives. Measured via ASTM D97.

Viscosity

Related to API gravity but not identical. Two crudes at the same API can have very different viscosities at a given temperature. Affects pumpability, pipeline friction losses, desalter performance, and heat exchanger efficiency. Canadian dilbit (diluted bitumen) is especially viscosity-sensitive.

Nitrogen content

Typically 0–0.6% by weight. Basic nitrogen compounds adsorb onto catalyst acidic sites, poisoning cracking and hydrotreating processes. Must be removed to meet fuel specs. Measured via ASTM D4629 (chemiluminescence). 20–35% of total nitrogen is "basic nitrogen" — the part that poisons catalysts.

Yield profile (distillation curve)

The most important property to a refinery planner. When you heat a barrel, what fractions boil off at each temperature? Measured via ASTM D2892 (true boiling point distillation). Two crudes with similar API/sulfur can have very different naphtha, kerosene, diesel, gas oil, and residuum yields — which directly determines the refinery's product revenue.

Section 02

The 30 most widely traded crude streams

These represent the most actively traded named streams in global markets. There are 200–300+ total, but these 30 cover the vast majority of international trade volume. Each producing field or blend point produces a stream with a distinct "fingerprint" of properties that varies slightly from cargo to cargo (like wine vintages). Sources: EIA, Wikipedia benchmarks list, S&P Global Platts assessed prices.

#	Crude stream	Origin	API	Sulfur	Type	Notable secondary properties	~Export volume
1	Brent	North Sea (UK/Norway)	38.3	0.37%	Light sweet	Low metals, low TAN. Global benchmark — prices ~70% of international crude.	~1M bpd blend
2	WTI Midland	Permian Basin, Texas, USA	41.5	0.18%	Light sweet	Very low sulfur/metals. Tight oil from shale. U.S. benchmark delivered at Cushing, OK.	~4M bpd exported
3	Arab Light	Saudi Arabia	33	1.8%	Light sour	Moderate V/Ni (~20/5 ppm). Aramco's primary export. OSP sets Asian crude pricing.	~5M bpd
4	Arab Medium	Saudi Arabia	28.5	2.6%	Medium sour	Higher metals than Arab Light. Feeds complex/deep conversion refineries.	~1.5M bpd
5	Arab Heavy	Saudi Arabia	27	2.8%	Medium sour	High V (~50 ppm). Needs cokers. Significant discount to Arab Light.	~0.8M bpd
6	Basrah Medium	Southern Iraq	28	2.8%	Medium sour	High metals, moderate TAN. Iraq's main export grade. Major to Asia/Europe.	~3M bpd
7	Basrah Heavy	Southern Iraq	24	3.6%	Heavy sour	Very high sulfur/metals. Deep discount. Needs deep conversion processing.	~0.5M bpd
8	Kuwait Export Crude	Kuwait	30.5	2.5%	Medium sour	Moderate metals. Feeds Al Zour domestically + Asian exports. KPC sets OSP.	~1.5M bpd
9	Murban	Abu Dhabi, UAE	39	0.8%	Light sour	Low metals, low TAN. Now a futures benchmark on ICE. ADNOC flagship grade.	~1.5M bpd
10	Upper Zakum	Abu Dhabi, UAE	33	1.8%	Light sour	Moderate metals. Second-largest UAE export grade. Feeds Ruwais refinery.	~0.6M bpd
11	Dubai	UAE (offshore)	31	2.0%	Medium sour	Asian pricing benchmark paired with Oman. Physical production declining.	~0.2M bpd
12	Oman	Oman	33	1.1%	Light sour	Lower sulfur than most ME grades. Co-benchmark with Dubai for Asian pricing.	~0.7M bpd
13	Urals	Russia (Western Siberia)	31	1.3%	Medium sour	Moderate metals/TAN. Was Europe's #1 sour supply. Post-2022 sanctions rerouted to India/China at deep discount.	~3M bpd
14	ESPO (Eastern Siberia)	Russia (Kozmino terminal)	35	0.6%	Light sour	Low metals. Premium to Urals. Exported primarily to China, Japan, South Korea.	~1.6M bpd
15	Western Canadian Select	Alberta, Canada	20.5	3.5%	Heavy sour	High viscosity (needs diluent for pipeline transport — shipped as "dilbit"). High V/Ni. ~95% exported to U.S.	~3M bpd
16	Cold Lake Blend	Alberta, Canada	22	3.8%	Heavy sour	Bitumen-derived. Very high viscosity. Similar market to WCS but slightly heavier.	~0.5M bpd
17	Maya	Mexico (offshore GOM)	21	3.3%	Heavy sour	High metals (~300 ppm V). Historically key USGC feedstock. Exports declining as Pemex expands domestic refining.	~0.6M bpd (declining)
18	Isthmus	Mexico	33	1.5%	Light sour	Mexico's lighter export grade. Moderate metals. Smaller volume than Maya.	~0.2M bpd
19	Merey	Venezuela (Orinoco Belt)	16	2.5%	Heavy sour	Very high metals (V ~350+ ppm). Needs diluent. Among lowest API of traded crudes. Mostly flows to China under sanctions.	~0.5M bpd
20	Bonny Light	Nigeria (Niger Delta)	35	0.14%	Light sweet	Very low sulfur/metals. High pour point (~5°C/41°F — waxy). Excellent gasoline yield. Premium West African grade.	~0.2M bpd
21	Agbami	Nigeria (deepwater)	47	0.04%	Light sweet	Ultra-light condensate-like. Almost zero sulfur. Very high naphtha yield. Dangote refinery's first cargo.	~0.2M bpd
22	Forcados	Nigeria	30	0.18%	Light sweet	Heavier than Bonny Light but still sweet. High pour point. Good middle distillate yield.	~0.2M bpd
23	Qua Iboe	Nigeria	35.3	0.12%	Light sweet	Premium benchmark for West African crude pricing. Low metals. High pour point (waxy).	~0.2M bpd
24	Girassol	Angola (deepwater)	31	0.34%	Light sweet	Low metals. Good middle distillate yield. Major Chinese import grade.	~0.2M bpd
25	Saharan Blend	Algeria	45	0.09%	Light sweet	Ultra-light, ultra-sweet. Very low metals. High naphtha yield. Dangote recently purchased cargoes.	~0.4M bpd
26	Es Sider	Libya	37	0.44%	Light sweet	Low metals. Mediterranean export. Subject to frequent supply disruptions due to Libyan instability.	Variable (~0.3M bpd)
27	Mars	U.S. Gulf of Mexico	28	2.0%	Medium sour	Moderate metals. Key USGC medium sour benchmark. Now part of NYMEX Mars futures.	~0.3M bpd
28	Eagle Ford	South Texas, USA	47	0.15%	Light sweet	Ultra-light tight oil. Very high naphtha content. Often exported as condensate. Low metals.	~1M bpd
29	Lula (Tupi)	Brazil (pre-salt offshore)	28	0.3%	Medium sweet	Relatively sweet for its weight. Brazil's pre-salt boom grade. Low TAN. Growing export volume.	~1M bpd (growing)
30	CPC Blend	Kazakhstan (via CPC pipeline)	44	0.55%	Light sour	Tengiz/Kashagan fields. Shipped via Black Sea. High wax content. European refinery feedstock.	~1.3M bpd

Why are there so many? Every producing field has unique geology that determines the chemical composition of its oil. When a pipeline blends output from several fields, the mix creates a new named stream. When new fields come online (like Guyana's Stabroek block or Brazil's pre-salt), new streams appear. When fields decline, streams shrink or merge into broader blends. The catalog is alive — it grows and shifts constantly. A single country like Nigeria has dozens of named streams (Bonny Light, Agbami, Akpo, Egina, Qua Iboe, Forcados, Brass River, Escravos, etc.) because each offshore field produces a distinct quality.

Section 03

Three tiers of refinery complexity

A refinery's installed equipment determines which crudes it can process profitably. The NCI (Nelson Complexity Index) quantifies this. No refinery runs just one crude — they blend 5–15 different streams per run using LP (linear programming) optimization. Sources: EIA complexity, Wikipedia NCI.

Tier 1 NCI 1–5

Simple (hydroskimming)

Atmospheric distillation + reformer + hydrotreater

Separates crude by boiling point. No upgrading of heavy fractions. Must run light sweet crude. Heavy crude exits as low-value residual fuel oil.

BP Rotterdam (NCI 5.3), Ireland Whitegate (NCI 3.8), many Eastern European, African, SE Asian facilities. Europe avg NCI: 6.5.

Tier 2 NCI 6–9

Complex (cracking)

Adds FCC (fluid catalytic cracker) or hydrocracker

Cracks heavy gas oil into gasoline/diesel/petrochemical feedstocks worth 30–50% more. Runs medium crudes optimally. Can run light sweet but the cracking units sit idle — economically suboptimal.

SK Ulsan 850K bpd, GS Caltex Yeosu 840K bpd, Dangote (NCI 10.5), Sarlux 300K bpd, Aramco Ras Tanura 550K bpd.

Tier 3 NCI 9+

Deep conversion (coking)

Adds delayed coker + extensive HDS (hydrodesulfurization)

Thermally breaks the heaviest residuum into lighter liquids and solid petroleum coke. Buys cheap heavy sour crude, invests in processing, captures the spread between discounted crude and premium products.

Jamnagar (NCI 21.1), Marathon Garyville, Valero Port Arthur (NCI ~14), ExxonMobil Baytown, ADNOC Ruwais, KIPIC Al Zour. U.S. avg NCI: ~11.

Section 04

Compatibility matrix

Not every refinery can eat every crude. Equipment determines the diet.

Optimal Limited Cannot

Crude type

Simple

Complex

Deep conv.

Light sweet

Optimal

Under-uses

Light sour

Limited

Good fit

Medium sour

With HDS

Optimal

Heavy sour

Optimal

Extra-heavy

With diluent

High-TAN

If alloy-upgraded

"Cannot" = economically unviable or equipment-incompatible, not always physically impossible in small blending ratios.

Section 05

How oil flows: source to refinery

Each region's crude quality determines which refineries can process it. Sources: Visual Capitalist 2024 trade flows, IEA Oil Market Report, Stillwater Associates.

U.S. shale (Permian)

WTI Midland, Eagle Ford

→

Light sweet

39–47 API, 0.1–0.2% S

→

Simple/complex (or exported)

Europe, Asia importers. USGC blends with heavy to optimize cokers. U.S. now world's largest producer (~13M bpd).

West Africa (Nigeria)

Bonny Light, Agbami, Qua Iboe

→

Light sweet

30–47 API, 0.04–0.2% S

→

Dangote + European simple refineries

Premium waxy grades (high pour point). Good gasoline yield. Dangote imports WTI when NNPC can't supply enough.

Middle East

Arab Light, Basrah, KEC, Murban

→

Light–medium sour

28–39 API, 0.8–2.8% S

→

Complex + deep conv. (Asia, domestic ME)

Jamnagar, SK Ulsan, SATORP, Al Zour. ~70% of Asian imports. New ME refineries add value domestically.

Canada (oil sands)

WCS, Cold Lake Blend

→

Heavy sour

20–22 API, 3.5–3.8% S

→

USGC deep conversion cokers

Marathon, ExxonMobil, Valero. 95%+ goes to U.S. TMX pipeline now pulls some west to Asia. Shipped as dilbit (needs diluent).

Venezuela (Orinoco)

Merey, Santa Barbara

→

Heavy / extra-heavy

8–16 API, 2.5% S, V 350+ ppm

→

USGC cokers (when sanctions allow)

Valero, PBF, Phillips 66 historically. Needs diluent. Mostly flows to China now. Some units were designed specifically for Venezuelan crude.

Russia

Urals, ESPO

→

Medium sour / light sour

31–35 API, 0.6–1.3% S

→

India + China (post-2022 reroute)

Was Europe's #1 sour supply. Post-sanctions, discounted barrels flow to Jamnagar and Chinese teapot refineries.

Section 06

Major refinery directory

Key facilities worldwide with complexity tier, crude diet, primary feedstock, and backup sources. Sources: Wikipedia refinery list, EIA Refinery Capacity Report, BOE Report USGC analysis.

Marathon GaryvilleLouisiana, USA

Capacity

596K bpd

Tier

Deep conv.

NCI

~12

Diet

Heavy sour

PrimaryVenezuelan heavy / Canadian WCS (heavy sour, <22 API, 2–3.5% S, high V/Ni)

BackupMexican Maya, Colombian Castilla (similar heavy sour profile)

FlexMars GOM, Arab Medium (medium sour when heavy supply tight)

Marathon Galveston BayTexas City, TX, USA

Capacity

631K bpd

Tier

Deep conv.

NCI

~12

PrimaryCanadian WCS, Venezuelan Merey (blended with Permian light sweet to optimize)

BackupMexican Maya, Colombian heavy grades

Valero Port ArthurPort Arthur, TX, USA

Capacity

395K bpd

Tier

Deep conv.

NCI

~14

PrimaryVenezuelan heavy, Canadian WCS (Valero historically top Venezuelan importer)

BackupIraqi Basrah Heavy, Saudi Arab Heavy, Mexican Maya

ExxonMobil BaytownBaytown, TX, USA

Capacity

584K bpd

Tier

Deep conv.

NCI

~13

PrimaryCanadian WCS, Mars GOM medium sour

BackupSaudi Arab Medium/Heavy, Iraqi Basrah, Venezuelan (when available)

Reliance JamnagarGujarat, India

Capacity

1.4M bpd

Tier

Deep conv.

NCI

21.1 (world record)

PrimaryMiddle East sour (Arab Light/Medium, Iraqi Basrah, Kuwait Export)

BackupWest African light sweet, Russian Urals (at deep post-sanctions discount)

NoteProcesses crudes ~5 API lower and 0.7% S higher than Indian peers. Petcoke gasifiers extract full barrel value. World's largest marine facility.

SK UlsanUlsan, South Korea

Capacity

850K bpd

Tier

Complex

PrimaryMiddle East grades (Arab Light, Kuwait Export, Murban)

BackupRussian ESPO, West African light sweet, US WTI exports

ADNOC RuwaisAbu Dhabi, UAE

Capacity

837K bpd

Tier

Deep conv.

PrimaryUAE Murban, Upper Zakum (domestic light/medium sour, 33–39 API)

BackupAlmost entirely domestic Abu Dhabi supply

KIPIC Al ZourAl Zour, Kuwait

Capacity

615K bpd

Tier

Deep conv.

PrimaryKuwait Export Crude (medium sour, 30.5 API, 2.5% S — domestic)

Dangote RefineryLekki, Lagos, Nigeria

Capacity

650K bpd → 1.4M

Tier

Complex (RFCC)

NCI

10.5

PrimaryNigerian grades — Agbami, Bonny Light, Forcados (light sweet, 30–47 API, low S)

BackupUS WTI Midland, Algerian Saharan Blend, Brazilian grades

NoteDesigned for 100% Nigerian crude but NNPC supply shortfalls force imports. Can process most African grades + Arab Light. Wikipedia.

BP RotterdamRotterdam, Netherlands

Capacity

400K bpd

Tier

Simple-mod.

NCI

5.3

PrimaryNorth Sea Brent, Forties, CPC Blend (light sweet, 37–44 API)

BackupWest African light sweet, US WTI exports

NoteDespite large capacity, low NCI limits ability to run heavy/sour. Typical of many European facilities.

Section 07

Seven mistakes rookie analysts make

Crude oil quality analysis is full of traps for the uninitiated. These are the errors that experienced traders and refinery planners see new analysts make most often. Sources: AFPM crude slate management Q&A, Penn State petroleum refining course, industry interviews.

Mistake #1

Treating crude oil as a single commodity

The most fundamental error: referring to "the price of oil" as if there's just one. At any given time, there are dozens of named crudes trading at different prices with differentials (diffs) of $2–$15+ between them. A barrel of Bonny Light (35 API, 0.14% S) and a barrel of Merey (16 API, 2.5% S) are as different as orange juice and motor oil in terms of what a refinery can do with them. When analyzing crude markets, always specify which crude and which benchmark differential you're looking at.

Mistake #2

Only looking at API gravity and sulfur, ignoring secondary properties

API and sulfur get you into the right neighborhood, but TAN (total acid number), metals content (vanadium, nickel), pour point, and nitrogen can make or break the economics. A crude might look attractive at 28 API and 1.5% S, but if it has a TAN of 2.0 mg KOH/g and 200 ppm vanadium, most refineries can't touch it without alloy-upgraded metallurgy and accelerated catalyst replacement. Opportunity crudes with bad secondary properties trade at steep discounts for a reason — the discount is the price of the hidden processing cost.

Mistake #3

Assuming any refinery can process any crude

A simple hydroskimming refinery in Eastern Europe (NCI ~4) literally cannot run heavy sour Canadian WCS, no matter how cheap it is. It doesn't have the coker to upgrade the heavy residuum or the HDS (hydrodesulfurization) units to remove the sulfur. Refinery configuration is a hard physical constraint, not an economic choice. When sanctions removed Venezuelan heavy barrels from the market, only the ~50% of U.S. refineries that have cokers were affected — the simple refineries that run domestic light sweet were untouched. Always check the refinery's NCI (Nelson Complexity Index) and unit configuration before assuming a crude-refinery match works.

Mistake #4

Confusing crude quality with crude value

"Better" crude (lighter, sweeter) is not always more profitable for a refinery. A deep conversion refinery (NCI 12+) makes its best margins on cheap, difficult crude — not expensive premium crude. When the light-heavy differential widens to $6–8/bbl, Gulf Coast cokers are "printing money" because they buy discounted heavy sour barrels and sell premium gasoline and diesel. Running light sweet crude in a coking refinery is like using a Ferrari to go grocery shopping — the capability is wasted. The economics depend on the spread between the crude's discount and the product's premium, not on crude quality alone.

Mistake #5

Forgetting that pour point and viscosity affect logistics, not just refining

Nigerian crudes like Bonny Light and Qua Iboe are premium grades with excellent chemistry, but they have high pour points (the temperature below which they stop flowing). If a tanker carrying Bonny Light crosses through cold North Atlantic waters in winter without heated cargo holds, the waxy crude can solidify — creating an extremely expensive problem. Similarly, Canadian WCS is shipped as "dilbit" (diluted bitumen) because the raw bitumen is too viscous to pump through pipelines without ~30% diluent (usually condensate). The diluent itself has to be shipped back to Alberta for reuse, creating a two-way logistics cost that's invisible if you only look at the crude price. Always factor in pour point (ASTM D97) and viscosity when evaluating transport routes.

Mistake #6

Treating assay data as fixed when it varies cargo-to-cargo

Crude streams are natural products, not manufactured goods. A cargo of Arab Light might be 32.8 API one month and 33.5 the next. Sulfur drifts. The yield curve shifts as wells age, new wells come online, or seasonal reservoir conditions change. Relying on a single "standard" assay from a database without checking the latest cargo-specific assay is how refinery planners get surprised by unexpected product yields, higher-than-expected hydrogen consumption in hydrotreaters, or corrosion incidents. AFPM recommends obtaining samples of new crudes before delivery and testing them against current refinery crude blends for compatibility.

Mistake #7

Ignoring how sanctions and geopolitics reshuffle trade flows, not just prices

When Russia was sanctioned in 2022, the obvious story was price. The deeper story was flow rerouting: ~3M bpd of Russian Urals that used to supply European refineries had to find new homes (India, China, Turkey), while those same European refineries had to find replacement medium sour barrels (Iraqi, Norwegian, Kazakh CPC Blend). This reshuffled shipping routes, tanker demand, freight costs, and regional price differentials in ways that persist years later. Similarly, when Venezuelan sanctions tightened, Gulf Coast cokers didn't just lose a crude source — they lost the specific quality profile their units were optimized for, forcing costly blend adjustments. When analyzing sanctions or geopolitical events, map the quality of the affected barrels to the specific refineries that process them, not just the headline volume.

Section 08

How the industry talks about crude

Nobody holds 300 crude streams in their head. They specialize by region, speak in differentials to benchmarks, and lean on pattern recognition built through years of exposure.

"I can offer you two cargoes of Bonny Light, April loading, at Dated Brent plus a dollar twenty."

Translation: Two shiploads (~950K barrels each) of Nigerian light sweet crude, loading onto tankers in April, priced at $1.20/bbl above the Brent benchmark when the pricing window hits. The buyer instantly knows: Nigerian, light sweet, premium quality, good gasoline yield, high pour point (will need heated cargo handling in cold climates) — and the exact relative price. No need to discuss API or sulfur. The name and the differential say everything.

"We're short on heavy sour this month. Mexico keeps cutting allocations and the WCS arb doesn't work with TMX pulling barrels to the coast. Can we pick up some Basrah Heavy or maybe a cargo of Castilla?"

Translation: Our coking refinery needs heavy crude but supply is tight. Mexico's Pemex is sending less Maya than usual. Canadian WCS is too expensive because the TMX (Trans Mountain Expansion) pipeline is pulling barrels west to the Pacific for Asian buyers, tightening Gulf Coast supply and shrinking the discount we need. So let's look at Iraqi heavy or Colombian heavy as alternatives — the coker doesn't care about origin, only that the API, sulfur, metals, and yield profile are close enough to the equipment's sweet spot.

"The light-heavy diff has blown out to six dollars. Complex refiners are printing money."

Translation: The price gap between light sweet crude (Brent/WTI) and heavy sour crude (Maya/WCS) has widened to ~$6/bbl. Deep conversion refineries capture this spread — they buy at the discount and sell premium products. When the diff widens, their margin (called the "crack spread") expands. Simple refineries that only run light sweet crude don't benefit at all — they're paying full price for premium crude regardless.

"Got a stem of Urals, CIF Rotterdam, first-half May. Any interest?"

Translation: "Stem" = tanker cargo. Urals = Russian medium sour (31 API, 1.3% S). CIF = seller pays shipping/insurance to Rotterdam. Post-2022 sanctions context is implicit — Urals is under a G7 price cap, European buyers have largely stopped taking it. This broker is fishing for someone willing to navigate compliance or reroute to India/Turkey. One sentence conveys quality, logistics, and geopolitical risk.

"We retooled our crude slate over three years. Used to run 60% heavy sour, 40% medium. Now we're 40/40/20 with domestic light sweet filling the gap. Shale guys are giving it away but our cokers are underutilized."

Translation: The shale revolution forced a strategic shift. Cheap light sweet crude flooded the market, so this coking refinery adjusted its blend. They added simpler distillation capacity ("topping units") for lighter barrels, but the expensive coking hardware — built specifically for Venezuelan/Mexican/Canadian heavy — now sits partially idle. It's the French-kitchen-reheating-pizza problem: they have capabilities they're not fully using because the cheap feedstock doesn't need them.

Name = geography

"Bonny Light" = Nigerian, light sweet, premium. "Merey" = Venezuelan, heavy, problematic. The name gets you 70% there.

Differentials to benchmarks

"Basrah Medium at Brent −$4.50" conveys quality, value, and price in one sentence. Most global crude prices as Brent ± something.

Category shorthand

"We need more heavy sour barrels" narrows 300 streams to ~15 candidates. Logistics and price narrow it further.

Assay databases

For precision, traders use Crude Monitor, Haverly, or LP software. Nobody memorizes that Qua Iboe is 35.3 API / 0.12% S — they look it up.

Section 09

Global refinery capability by region

Sources: EIA Global Refining Outlook 2024, IEA Oil Market Report, Wikipedia refinery list.

U.S. Gulf Coast Deep conversion Avg NCI ~11

World's deepest conversion capacity at ~9.6M bpd. Built for heavy Western Hemisphere crudes. Coking/hydrocracking = ~29% of capacity. Currently competing for heavy supply after Venezuelan sanctions and declining Mexican exports. U.S. refineries were retooled in the 1990s-2000s with upgraded steel and expanded cokers specifically for Latin American heavy sour.

India Deep conv. Complex

Jamnagar (NCI 21.1) is the world's most complex refinery. Selected as partner for Trump's proposed Texas refinery because of this expertise. Public-sector refineries (IOCL, BPCL, HPCL) at NCI 10–12.6. Now taking discounted Russian Urals post-sanctions, adding to Middle Eastern imports.

China Complex 18.5M bpd

World's largest refining capacity since overtaking the U.S. in 2023. Added 5.5M bpd (2011–2023). Mix of state giants (Sinopec, CNPC, CNOOC) and private "teapot" refiners. Increasingly processing sanctioned crude (Russian, Iranian, Venezuelan) at discounts.

South Korea Complex

SK Ulsan (850K bpd) and GS Caltex Yeosu (840K bpd) among world's largest. Zero domestic crude — 100% imported, primarily Middle Eastern sour. Major refined product exporter across Asia.

Middle East Deep conv. 10.8M bpd

New mega-refineries (SATORP, Jazan, Al Zour, Ruwais). Strategy: add value domestically from their own crude rather than export raw barrels. NCI 7–12 across the region.

Europe Simple Complex (mixed) Avg NCI ~6.5

Rotterdam and Mediterranean have moderate complexity. Eastern Europe has many simpler, older facilities. Lost Russian Urals supply post-2022. No top-10 global refineries. Under competitive pressure from Asian and Middle Eastern mega-refineries.

Africa Simple + Dangote NCI 10.5

Historically small, unreliable refineries. Dangote (650K bpd → 1.4M) is a game-changer — Africa's first world-class facility. Designed for Nigerian light sweet crude. Nigeria's state refineries (Port Harcourt, Kaduna, Warri) have been idle for years despite $18B+ spent on rehabilitation.

Section 10

"So You Think You Can Model Energy?" — A Quick Quiz

Before you build another lifecycle analysis spreadsheet or tweet about "just switching to renewables," see if you can answer these questions that any petroleum engineer would consider basic.

Who this is for: Physicists, electrical engineers, computer scientists, mechanical engineers, civil engineers, neuroscientists, and self-proclaimed "polymaths" who've never touched petroleum, chemical, systems, or geological engineering — or survived in the analog trenches where paranoia is the only thing keeping things from exploding — who think they can do a real lifecycle energy or cost analysis.

Q1: What's the API gravity range where a barrel stops being "light sweet" and becomes your refinery's worst nightmare?

And no, you can't Google it — your model should already know this. Hint: The answer involves both gravity AND sulfur thresholds, and it varies by refinery configuration.

Q2: You're comparing two crudes: one at 0.5% sulfur, one at 2.8%. How many additional processing steps does the sour crude require before it's street-legal diesel?

Hint: It's not "one desulfurization unit." Think HDS capacity, hydrogen consumption, catalyst regeneration, and sulfur recovery.

Q3: A cargo of Maya crude just arrived. What hydrogen consumption (in SCF/bbl) does your coker need to turn that asphaltic mess into something resembling gasoline?

Oh, you thought all barrels were equal? Maya's 21.5° API and 3.4% sulfur content means your hydrotreaters are working overtime.

Q4: What's the TAN (Total Acid Number) threshold where your distillation column starts corroding faster than your career credibility?

Answer: ~0.5 mg KOH/g is where problems start. Above 1.0, you need stainless steel or face accelerated equipment failure. Your generic refinery model doesn't track this.

Q5: You've got a 250,000 bpd refinery optimized for Brent. Someone sends you Basrah Heavy instead. What's your yield loss on the light ends — and why is your spreadsheet suddenly crying?

Brent: 38° API. Basrah Heavy: 24° API. That's ~15% less gasoline/naphtha yield and your FCC is now drowning in residue it wasn't designed to handle.

Q6: Explain why a barrel of Canadian oil sands dilbit requires ~30% diluent by volume just to flow through a pipeline — and where that diluent comes from.

Spoiler: The diluent (condensate or naphtha) isn't free energy. It's often shipped FROM the refinery back to Alberta, then returned with the bitumen. Your EROEI calculation probably ignored this loop.

Q7: What's the EROEI difference between a conventional Saudi Ghawar barrel vs. a Venezuelan extra-heavy Orinoco barrel?

Off by more than 3:1? Back to your fluid mechanics homework. Ghawar: ~20:1. Orinoco after upgrading: ~6:1 to 8:1. Not the same "barrel."

Q8: Why can't a simple hydroskimming refinery process most of the crude produced today?

"Just add heat" isn't an answer. Reality: ~70% of global crude requires cracking or coking capacity that simple refineries don't have. The "light sweet" your model assumes is <14% of world production.

Section 11

The Refinery Reality Check

Here's what you're up against. There are approximately 825 refineries globally (2024), and they are NOT created equal.

Refinery Type	NCI Range	Global Count	% of World	Crudes (of Top 30)	Streams (of ~160)
Hydroskimming (Simple)	<6	~65-80	~10%	8-12 only	~25-30
Cracking (Medium)	6-10	~325-400	~50%	18-22	~70-90
Coking (Complex)	>10	~230-285	~35%	All 30	~140-160
Topping (Minimal)	<2	~40	~5%	3-5 only	~10-15

Where Each Type Lives (Because Geography Matters)

Refinery Type	Regional Distribution
Hydroskimming	Europe (avg NCI ~6.5): Mediterranean, Scandinavia, Eastern Europe; Japan; Russia; legacy plants in Africa and South America
Cracking	Canada (avg NCI >8); Western Europe; India; Southeast Asia; Australia; most of China's older stock
Coking/Complex	US Gulf Coast (avg NCI >13): 25+ facilities; US Midwest: 15+; California: 10+; China's new builds; Middle East mega-refineries; India's Jamnagar
Topping	Alaska (remote locations); small Caribbean facilities; West Africa legacy plants

Continent-by-Continent Breakdown

Continent	Total Refineries	Dominant Type	Notes
North America	~150	Coking/Complex	US has 132 operable; Canada ~15; highest avg complexity globally (70%+ are NCI >10)
Europe	~100	Cracking/Hydro	Avg NCI ~6.5; cannot process heavy sour; many closures since 2010; no top-10 global refineries
Asia-Pacific	~270	Mixed	China: 40+; India: 23; Japan: 22 (many simple); new mega-refineries all coking
Middle East	~50	Complex/Integrated	Export-focused; Kuwait, Saudi, UAE have NCI >12 facilities
South America	~60	Cracking	Aging fleet; Venezuela's Paraguana is world's largest but deteriorating
Africa	~45	Simple/Topping	Most can only run light sweet imports; Dangote is changing this
Russia/CIS	~50	Hydroskimming	Soviet legacy; low complexity; modernization underway

Q9: A hydroskimming refinery in Rotterdam receives a cargo of Mars Blend (28° API, 2.0% sulfur) instead of their usual Brent. What percentage of that barrel becomes unsellable residual fuel?

And why can't they just "process it anyway"? Answer: ~40-50% residual fuel vs ~20% with Brent. No coker means no way to upgrade the bottoms. They'd have to sell it at a deep discount or refuse the cargo entirely.

Q10: Your lifecycle model assumes "average US refinery emissions." But the US has facilities ranging from NCI 1.8 to NCI 21.4. What's the CO₂ intensity difference between them?

A simple refinery processing Arab Extra Light vs. a coking refinery processing Cold Lake Dilbit — the difference is 2-4x in refinery emissions alone. Your single number captures exactly none of this.

Q11: Name 5 crude streams that CANNOT be processed by any refinery in Europe without first being blended with lighter feedstock.

Examples: Western Canadian Select, Cold Lake Dilbit, Maya, Merey, Basrah Heavy. This is why 90% of Canadian oil sands production goes to PADD 2 and PADD 3 instead of crossing the Atlantic.

Q12: You're building an energy model for "global refining." Which of these inputs did you specify?

☐ Refinery complexity distribution by region
☐ Crude slate API gravity range
☐ Sulfur processing capacity (HDS units)
☐ Coking vs. cracking vs. hydroskimming split
☐ Hydrogen consumption by configuration

If you checked fewer than 3, your model is a cartoon.

Q13: A pipeline operator announces they're switching from Bakken Light (42° API) to Western Canadian Select (20.5° API). Does pipeline capacity go up or down — and by roughly what percentage?

Answer: DOWN by ~15-25%. Heavier crude = higher viscosity = more friction = slower flow = less throughput. Your "barrels are fungible" assumption just broke the pipeline's economics.

Q14: There are approximately 160 actively traded crude streams globally. A hydroskimming refinery can process ~25 of them. What's the name of the OTHER 135?

They're the ones your "barrels are fungible" assumption just erased from existence. Medium and heavy sours that require cracking or coking capacity that 10% of world refineries simply don't have.

Section 12

The Crude Reality — Production by Grade

Because "83 million barrels per day" is meaningless without knowing WHAT'S in those barrels. Global crude production (2024): ~83 million BPD.

Crude Grade	API°	Sulfur %	Type	Production (BPD)	Market Share	Source	Processable By
WTI	39.6	0.24	Light Sweet	~4.5M	5.4%	USA (Permian)	All types
Brent Blend	38.3	0.37	Light Sweet	~1.0M	1.2%	North Sea	All types
Arab Light	32.8	1.77	Medium Sour	~5.0M	6.0%	Saudi Arabia	Cracking+
Arab Heavy	27.4	2.80	Heavy Sour	~1.5M	1.8%	Saudi Arabia	Coking only
Dubai/Oman	31.0	2.00	Medium Sour	~2.8M	3.4%	UAE/Oman	Cracking+
Urals	31.7	1.35	Medium Sour	~4.5M	5.4%	Russia	Cracking+
ESPO	34.8	0.62	Light Sour	~1.6M	1.9%	Russia (Pacific)	Cracking+
Basrah Light	29.5	2.90	Medium Sour	~2.8M	3.4%	Iraq	Cracking+
Basrah Heavy	24.0	3.80	Heavy Sour	~0.9M	1.1%	Iraq	Coking only
Maya	21.5	3.40	Heavy Sour	~1.0M	1.2%	Mexico	Coking only
Western Canadian Select	20.5	3.50	Heavy Sour	~3.8M	4.6%	Canada (Oil Sands)	Coking only
Cold Lake Dilbit	20.0	3.80	Heavy Sour	~0.8M	1.0%	Canada (Alberta)	Coking only
Bonny Light	35.4	0.14	Light Sweet	~1.2M	1.4%	Nigeria	All types
Iranian Light	33.4	1.36	Medium Sour	~2.0M	2.4%	Iran	Cracking+
Kuwait Export	30.5	2.55	Medium Sour	~2.5M	3.0%	Kuwait	Cracking+
Murban	40.5	0.78	Light Sour	~2.0M	2.4%	UAE	All types
Lula (Tupi)	28.0	0.35	Medium Sweet	~1.8M	2.2%	Brazil (Pre-salt)	Cracking+
Bakken	42.0	0.19	Light Sweet	~1.2M	1.4%	USA (N. Dakota)	All types
Eagle Ford	47.0	0.15	Ultra-Light Sweet	~1.0M	1.2%	USA (Texas)	All types
Saharan Blend	45.0	0.09	Light Sweet	~0.9M	1.1%	Algeria	All types

The Uncomfortable Summary

Crude Category	Total Production	Market Share	Refineries That Can Run It
Light Sweet (>35° API, <0.5% S)	~12M BPD	14%	All 825 refineries
Medium Grades (25-35° API)	~35M BPD	42%	~700 refineries (Cracking+)
Heavy Sour (<25° API, >2.5% S)	~12M BPD	14%	Only ~285 coking refineries
Other/Condensates	~24M BPD	30%	Varies

The Punchline: ~14% of global crude production can ONLY be processed by ~35% of world refineries (cokers). Your "average barrel" doesn't exist. 42% of production requires cracking capacity that European hydroskimmers don't have. And that Canadian heavy your model lumped with WTI? It needs 30% diluent by volume just to flow through a pipe — energy your EROEI calculation probably ignored.

Scoring

How did you do?

0-3 correct: You're exactly the person this section is about. Please stop publishing energy analyses.

4-7 correct: You've at least Googled some things. Still dangerous.

8-11 correct: You might actually know what crude quality means. Suspicious. Are you sure you're not a ChemE?

12+ correct: You've worked a turnaround at 3am covered in cat-cracker dust. You may proceed.