Seven Sisters Petroleum was an oil corporation in Mad Max and Mad Max 2 they're based off the real life group of oil companies that existed to the 1940s to the 1970s which comprised of Anglo-Persian Oil Company (now BP); Gulf Oil, Standard Oil of California (now Chevron), Texaco (later merged with Chevron); Royal Dutch Shell; Standard Oil of New Jersey (Esso/Exxon)and Standard Oil Company of New York (Socony) (trading as Mobil now part of ExxonMobil). 
The 7 Sisters Petroleum is the main oil supplier in the Mad Max movies. The war in the Middle East between Saudi Arabia and Iran left the oil fields ablaze which started the economical collapse due to lack of oil across the globe. 7 Sisters Petroleum was not able to fulfill their contracts with governments which cause major oil shortages and escalation of chaos and violence among the population across the world. The prices of oil quadrupled and skyrocketed overnight which started the spiral of violence on the roads over oil. In Mad Max the 7 Sisters Petroleum tanker trucks are under constant attacks and are victim of one such attack by the Toecutter's gang. In an early draft of Mad Max 2 it is revealed that Papagallo used to work for the company before it collapsed. Due to impending chaos and the fall of society, Papagallo took the maps revealing the location of the oil refinery in the wastelands. The oil refinery was property of 7 Sisters Petroleum seeing as it has their tanker inside. The 7 Sisters Petroleum most likely dissolved shortly after the events of Mad Max.
Their logo is inspired by Gulf Oil's logo.