The petroleum industry can be divided into three parts. They can be upstream, midstream and downstream.
The upstream portion is also called the exploration and production sector. This includes searching for crude oil and natural gas underground or underwater through drilling. The drilling brings the crude oil and natural gas up to the surface for harvesting. Unconventional gas can sometimes be included in the upstream sector as well as liquefied natural gas. The upstream and oil and gas midstream sectors work together but rarely overlap. Most upstream oil and gas companies are called ‘integral’ because use all three sectors of upstream, midstream and downstream, combining them to work together.
The midstream portion refers to the transportation storage and marketing of crude or refined petroleum. Transpor