INTRODUCTION

It is more than a century since oil barrels are no longer used to physically move or store oil and refined liquids, but the term 'barrel' persists across the industry as a unit of measure for oil trading and converting into refined products. The transition away from physical barrels was gradual, occurring primarily between the 1870s and early
1900s.

Here's how the evolution unfolded:

EARLY TRANSITION (1870s-1890s)

The first major shifts away from physical barrels came through multiple innovations:

🛢 Small tanker boats enabled barrel-free river shipments in the early 1870s.
🛢 Ludvig Nobel developed the first ocean tanker, the Zoroaster, in the late 1870s for Caspian Sea transport.
🛢 Pipeline systems emerged, with the first commercial line running five miles from Pithole City, Pennsylvania to Oil Creek in 1865.
🛢 Railway tanks replaced barrel-filled boxcars.
🛢 Horse-drawn kegs were used for local distribution.

FINAL PHASE-OUT (1890s-1950s)

Several developments marked the end of the barrel era:

🛢 By the 1890s, longer pipelines connected Oklahoma and Gulf Coast fields to Illinois refineries.
🛢 In 1905, Nellie Bly patented the modern 55-gallon steel drum, which helped separate the physical barrel from the 42-gallon measurement unit.
🛢 By the 1950s, the widespread adoption of pipelines, rail tanks, and tanker trucks meant very little oil needed to move in physical barrels.

LEGACY USE

After the 1950s, physical barrels found alternative uses in ports for raw materials and ship fuel, though many ended up in junkyards as evidence of their obsolescence.

🛢 The term "barrel" persisted as a unit of measurement (42 gallons) despite the physical container no longer being used for oil transport.

OIL AND REFINED LIQUIDS AND GASES ARE MEASURED IN VOLUME UNITS

Worse even, barrel is a volume unit, not a mass unit.

Excepted for solid products like coal or polymers that are measured in metric tonnes—it would certainly be inadequate and a bit challenging to fill a barrel with coal balls or polymer pellets—both liquids and gases moved into and across the refinery remain measured in volume units, more than 100 hundred years after their use ended.

Gaseous feedstock is measured in abstract units such as million SCUF (Standard Cubic Foot) such as is the case for methane or ethane, or in other situations when the gases are actually manufactured such as hydrogen, nitrogen, oxygen, etc. they are measured in Normal Cubic Meter per day (NCM/d).

DECEPTIVE TRANSPARENCY

Not only is this situation confusing since I have never come across anyone able to spontaneously make the link between volumes such as 100,000 b/d of crude oil, 100 million SCUF/d of ethane, or 1 million NCM/d of hydrogen to the corresponding product mass in tonnes per day or per year, but the volume to mass conversion also depends both on the product characteristics such as the liquid density which varies broadly across crude oil types and refined liquids, or on the measurement conditions such as gas pressure and temperature, which are the source of considerable variations in the estimated mass quantities.

It sounds to me that this is purposefully maintained confusion on the side of the industry stakeholders, as reporting capacity or actual production rates in volume is a deceptive practice preventing shareholders and investors to sneak peek into the internal workings of the refinery and the adequacy of its configuration or to challenge process efficiency or the soundness of refinancing an existing activity or investing into a capital project.

HOW DO YOU DEAL WITH THIS?

By far the weakest point in the engineering and mass balancing of a refinery or petrochemical complex is to apprehend the holistic and detailed product flows from imported feedstock to commercial products via intermediate product streams, emissions and waste products.

My question to chemical engineers, project managers, facility planners and technology specialists is this:

How do you deal with a situation such as this one, where under the guise of transparency, all product flows are represented in volume flows and lacking the necessary granularity to recreate a model, whether it is Linear Programming, Process Flow Diagram or a detailed Mass Balance of the refinery?

While this example stands as one of the most detailed and accurate refinery descriptions available, it still falls far short of enabling accurate modeling of refinery operations, underscoring the broader challenge of an industry characterized by opacity and minimal operational disclosure.

INFORMATION SOURCES

1. Brian Jacobson, 8^th Sep 2017, Oil Barrels Aren't Real Anymore, The Atlantic.
2. F. Gerali, 2019, Barrel (Unit of Measurement), Engineering and Technology History Wiki.
3. History of oil transportation, International Association of Oil Transporters. (Accessed 2^nd Jan 2025)
4. Energy and Mining Innovation, 1^st  Jun 2023, Pipelines for Beginners - How does an oil pipeline work?, Youtube.com
5. Wikipedia, Barrel (unit). (Accessed 2^nd Jan 2025)

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