The average specific gravity of crude oil processed by U.S. refineries has become increasingly lighter since 2011, according to a note from the U.S. Energy Information Administration (EIA).
In the note, the EIA said that the rise had been most pronounced among plants located near the coast of the Gulf of Mexico. Between 2011 and 2018, it stated, the average specific gravity of crude processed in these plants climbed from 30.0° API to 32.6° API in 2018.
The main factor in this shift has been higher output of light crude oil – that is, oil with a specific gravity of more than 40° API – within the U.S. itself, the EIA stated. Light grades represent the fastest-growing category of domestic production, and average yields have moved from 4.6 million barrels per day (bpd) in 2015 to 6.4 million bpd in the first seven months of 2019, it added.