What Is In A Barrel Of Oil?

Basic refinery

After my recent post (on my politics blog) about oil reserves around the World, I received a comment with a couple of questions that I thought might make a good follow-up article on this blog.

okay. I’ve always wanted to ask this question of someone, now’s my chance….. hope you have the answer Paul…..

How many gallons (or even litres!!) are there in one barrel (in terms of crude oil I think).

You would expect there to be an easy answer, but it is muddied somewhat by different definitions of barrels and gallons, but official values based on Oil Industry standards;

A US Barrel of oil is 159 litres which is about 35 UK gallons or 42 US gallons

The second question was even more interesting;

I realise crude needs to be refined to get what we call petrol etc, so maybe a secondary question, how many gallons of petrol do we get from one barrel?

A barrel is a bit of a difficult measurement to be clear upon, whereas at least gallons or litres are easier to visualise in everyday terms

The amount of petrol (gasoline) that is distilled from a barrel of crude oil depends on the type of crude, which varies enormously across the World.  There are many variables and impurities including; sulphur, metals, paraffins (wax), nitrogen, oxygen etc. that all impact the way the crude is processed.

The main variable however is the assay of the crude which determines how much of the various fractions are present to form the main refinery products; natural gas, propane/ butane, gasoline, diesel, fuel oil, heavy fuel oil, bitumen etc.

There are a number of grades of crude oil; ‘Light’ or ‘Extra Light’ contain larger quantities of gasoline and are correspondingly more expensive. A medium crude contains less gasoline and more heavier material. A heavy crude may contain 70% heavy material and is very difficult (and expensive) to process but is also a lot cheaper.

The aim of a modern refinery isn’t normally to just separate the various components of a barrel, but also to ‘upgrade’ heavy products into lighter, more saleable products through a number of energy intensive (usually high temperature and high pressure) processes.  These cause the longer heavier carbon chains to ‘crack‘ into shorter lighter (more valuable) chains.

Different refineries are set up in different ways. Some aim to produce more gasoline, others more diesel. Some will specialise in ‘bottom of the barrel’ processes – meaning they are built to process heavy crudes and residues – others will be simple topping or hydroskimming refineries.

It is therefore difficult to to give a specific answer, but after looking over a range of refinery outputs of different types, a ‘typical’ barrel of oil will generate something like;

Product 159
Gasoline 47% 74.73 litres
Heating Oil/ Diesel Fuel 19% 30.21
Jet Fuel (Kerosene) 11% 17.49
Natural Gas Liquids (Propane, Butane etc.) 6% 9.54
Natural Gas 4% 6.36
Other 13% 20.67

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