The Petroleum industry globally is second to the manufacturing sector globally. It entails extraction after exploration of hydrocarbon deposits in the earth crust. The industry also entails the distribution and marketing of the various Petroleum Products like gasoline, DPK, bitumem, various industrial and domestic gases etc.
Most of these products are either consumed domestically or exported to other nations which are not priviledged with hydrocarbon endowment. Since this is a global phenomenon and trade which is pivotal to every economy's growth, its commerce is denominated in dollars.
The monetary values generated within the industry value chains is so humongous as compared to that from other industries hence it is dubbed "Petrodollars"!!
Wouldn't you rather invest in the Petroleum industry??