HOUSTON, Oct. 9 (Xinhua) -- As domestic production continues to increase, the average density of crude oil produced in the United States continues to become lighter, the U.S. Energy Information Administration (EIA) said on Tuesday.
The average API gravity -- a measure of a crude oil's density where higher numbers mean lower density -- of U.S. crude oil increased in 2017 and through the first six months of 2018.
EIA reported that crude oil production with an API gravity higher than 40 degrees grew by 310,000 barrels per day to more than 4.6 million barrels per day in 2017. This increase represents 53 percent of total Lower-48 production in 2017, an increase from 50 percent in 2015, the earliest year for which EIA has oil production data by API gravity.
API gravity is measured as the inverse of the density of a petroleum liquid relative to water. The higher the API gravity, the lower the density of the petroleum liquid, meaning lighter oils have higher API gravities.
The increase in light crude oil production is the result of the growth in crude oil production from tight formations enabled by improvements in horizontal drilling and hydraulic fracturing.
API gravity can differ greatly by production area. For example, oil produced in Texas -- the largest crude oil-producing state -- has a relatively broad distribution of API gravities with most production ranging from 30 to 50 degrees API.
However, crude oil with API gravity of 40 to 50 degrees accounted for the largest share of Texas production, at 55 percent, in 2017. This category was also the fastest growing, reaching 1.9 million barrels per day, driven by increasing production in the tight oil plays of the Permian and Eagle Ford, both located in eastern Texas.
As domestic production continues to increase, EIA forecast that U.S. oil production from tight formations will continue to increase in the coming decades.
In contrast to the increasing production of light crude oil in the United States, its imported crude oil continues to be heavier.
Last year, 7.6 million barrels per day, or 96 percent, of imported crude oil by the United States had an API gravity of 40 or below, compared with 4.2 million barrels per day, or 48 percent, of its domestic production.
EIA collects API gravity production data to better inform analysis of refinery inputs and utilization, crude oil trade, and regional crude oil pricing.
