The consortium agreement of 1954 was also revised in 1974 and a new agreement replaced it . Decisions of the Organization of Petroleum Exporting Countries ( OPEC ) , which were implemented , by member countries, including Iran , further restricted the operations of foreign companies .Concession holding companies practically turned into Oil-exporting countries’ service contractors in the late 70s .Their tax payments had increased from 50 % to 80 % and their royalty payments from 12.5 to 20 % . Oil prices were also set by producing countries . Thus ,foreign companies were left with just 22 cents per barrel . Consortium member companies had to lift and export much of the crude oil they produced . They also had to process 300 thousand b/d of crude oil in the Abadan refinery and export products . In addition , they had to pay NIOC , 40% of capital expenses , interest-free as down payment for the crude oil produced . They were also obliged to provide NIOC , with all technical services required for operations , for a period of 5 years . because of limitations imposed on companies as a result of OPEC decisions , the implementations of those commitments became difficult . The situation became intolerable for The consortium after the 1953 agreement , and called for the resumption of negotiations aimed at reaching a new agreement . Negotiations started in 1976 and went on up to the victory of the Islamic Revolution , and never came to positive results . With the culmination of the Islamic Revolution led by the late Imam Khomeini , the National Iranian Oil Company ( NIOC ) officially declared the end of Iran’s relations with Consortium member companies .later on , all exploration and production contracts that had been signed with foreign companies before the revolution were declared as null & void , based on the Revolutionary Council decision of 7th Jan. 1979.