Why is oil measurement generally done in units of “barrels”?

In 1859, the American Drake discovered an oil field in Titusville, Pennsylvania, and he dug 24 wells. In 1860, 90,000 tons of crude oil were produced. Where to put all this liquid petroleum? So he used whale oil barrels with a capacity of about 8 beer barrels to store it. When there was too much to hold, he had no choice but to dig pits in the ground to temporarily store the oil that couldn’t be put into barrels right away. Then, it was packaged in individual beer barrels and sent to various refineries. This story established the relationship between barrels and oil. Initially, oil transactions were carried out in barrels. However, the wooden barrels used to hold oil come in different sizes; the weight of the oil received by each oil dealer from various refineries varies from barrel to barrel, and there are also no uniform standards regarding the pricing and taxes to be applied. Therefore, before 1876, the United States adopted a standard that was acceptable to both British and American merchants, fixing 42 gallons as one barrel. Later, the barrel became a universally accepted unit of measurement for oil around the world. However, the barrel is primarily a unit of measurement for oil used by OPEC and Western countries such as the United States and Britain; in countries like China and Russia, tons are used as the unit for measuring oil. If we do the conversion, 1 barrel is approximately 159 liters, so 1 ton is roughly equivalent to 7 barrels

Currently, the volume of one barrel of oil is 159 liters or 42 U.S. gallons. Before the 1860s, people used wooden barrels as containers, with capacities ranging from 150 to 190 liters. 　　Starting in 1865, with the construction of oil pipelines and the increased use of storage tanks, bulk carriers, and oil tankers, oil was rarely transported in barrels anymore. In 1972, the Organization of Petroleum Exporting Countries adopted the 42-gallon barrel as the standard unit of measurement for oil.

Around the 4th century AD, historical records indicate that the Chinese drilled the first natural gas well in Sichuan, at a depth of about 243 meters; bamboo poles were used to bring the natural gas to the surface, where it was burned to evaporate brine and produce salt. By the early 8th century, the new streets in Baghdad, Iraq, were paved with natural asphalt. 　　For the next few hundred years, the energy sources used by people remained mainly coal and biofuels. In 1852, Poland established what can be considered the first modern oil field. Since then, oil fields have been discovered around the world, and oil has played an important role in global politics, economies, the environment, industry, and wars. It has generated wealth for some countries, but it has also caused numerous crises worldwide. 　　The barrel is made by binding strips of oak or other woods together and encircling them with iron plates. Typically, the waist of a wooden barrel is made round and bulgy so as to facilitate rolling on the ground, reduce friction, and make it easier to change the direction of rolling; moreover, the principle of a circular shell is used to distribute the load. 　　The barrel truly became associated with oil on August 27, 1859, when the American Drake discovered an oil field in Titusville, Pennsylvania. Drake dug pits at the drilling site to create oil ponds for storing the oil, then poured it into beer barrels one by one. These barrels were transported by cart to the river, where the oil was loaded onto boats and shipped to refineries throughout the region. This story created an inseparable relationship between oil and barrels. 　　When Rockefeller founded Standard Oil in 1870, he made extensive use of wooden barrels produced by his family, establishing a standard delivery size of 42 gallons per barrel; he also painted the barrels blue to distinguish them from those made by other manufacturers. At that time, oil was traded in barrels; different oil traders obtained oil from various refineries, and the quantity of oil each received per barrel varied. As a result, there were no standards for pricing or taxation. Therefore, it became an urgent task for the parties involved in oil trading, as well as the tax authorities acting as intermediaries, to establish a standard barrel volume. Thus, before the Civil War in 1876, the United States adopted a standard that could be accepted by both British and American merchants, setting 42 gallons as one barrel. This standard petroleum measurement unit, the barrel (with 4.54609 liters per gallon, so 1 barrel is approximately 190 liters), has since become the unit used for trading crude oil worldwide.