There are two major sectors within the oil industry: "Upstream" is the process of exploring for oil and gas, extracting it from the earth, and "Downstream" refers to the process of refining it.

Companies involved in the upstream oil and gas business include exploration and production companies, and drilling and oilfield service companies. While this sector is a highly fragmented industry with multiple players in virtually every sector, the refining or "downstream" business is dominated by a handful of large integrated oil companies. ("Integrated" because many of these companies look after all factors of production, refining, and marketing, such as Exxon Mobil and BP.)

At PetroPortfolio, we are focused primarily on the exploration segment of the upstream sector. Unlike most large integrated firms, the economics of discovery dictate a significantly greater effect on share price for the independent companies who dominate exploration activities in many of the most promising, underdeveloped, or new hydrocarbon provinces.