We annually research 187 global Oil & Gas companies. Combined, they employ over 6 million full-time equivalent employees and generate trillions in annual revenues. Oil & Gas companies are categorized by streams. "Upstream" and "Downstream" are industry business terms referring to a company's location in the supply chain. Raw material extraction or production are elements of the supply chain considered to be upstream. The closer to the end user, it is said to be downstream. These 20 brand name companies offer a good geographic perspective, as well as their combination of both operational streams.