how many countries are a part of it?
13 countries
OPEC
 13 member countries accounted for an estimated 44 percent of global oil production and 81.5 percent of the world's "proven" oil reserves,
who controls the oil in the middle east OPEC what does it stand for? Organization of the Petroleum Exporting Countries when was it formed? 14 September 1960 where is it headquartered in? Vienna, Austria
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OPEC [SEP] Introduction
The Organization of the Petroleum Exporting Countries (OPEC, ) is an intergovernmental organization of nations. Founded on 14 September 1960 in Baghdad by the first five members (Iran, Iraq, Kuwait, Saudi Arabia, and Venezuela), it has since 1965 been headquartered in Vienna, Austria, although Austria is not an OPEC member state. , the 13 member countries accounted for an estimated 44 percent of global oil production and 81.5 percent of the world's "proven" oil reserves, giving OPEC a major influence on global oil prices that were previously determined by the so-called "Seven Sisters" grouping of multinational oil companies. A larger group called OPEC+ was formed in late 2016, to have more control on global crude oil market.