The majority of crude oil produced in the USA tilts to the sweet category. This means lighter hydrocarbons and lower sulfur compounds. The majority of USA import oil is the opposite and tilts sour. Sour means heavier hydrocarbons and more sulfur.
Most if not all refineries on the gulf coast for example, blend light sweet and heavy sour crude oils to get the optimal ratio to meet market demands of the moment and to keep the crude oil feed composition in the range the refinery is designed to economically operate in.
In the 1990s, I did a mass balance for a crude oil refinery on the gulf coast. 9 month project. For the crude oil feed, the feed stock was largely West Texas Intermediate blended with imports from the Middle East, Mexico and Venezuela. These four crude varieties were blended In constantly varying ratios to tweak the feedstock composition to the crude unit to match refined product demands.
I got a kick out of the crude tanker imports. From the tanker reports, let's say a long haul from the Middle East, a tanker would sail typically sail a direct course to the Atlantic Ocean. After that, zig zags would happen as the oil was bought and sold. Original destination Chesapeake Bay would change to New Orleans. A few days later, another sale and now headed to Beaumont.
Thanks for the info. It’s an interesting subject.
Seems like I read somewhere that part of the purpose of the Keystone Pipeline was to pump some of our “light” shale oil to Canada to mix with their “heavy” product from their tar sands fields, then send the mix back to the US as a more ideal blend to be refined. Is that correct?