"Shah of Iran announces that the 1954 operating agreement between a consortium of oil companies and Iran will not be renewed when it expires in 1979. The consortium was formed in 1954 as a means to settle a dispute between a new ministry in Iran and the Anglo-Iranian Oil Company (AIOC). The consortium included Standard Oil of New Jersey, Standard Oil of California, SOCONY-Vacuum, the Texas Company, Gulf, Royal Dutch-Shell, the Compagnie Francaise de Petroles, and the AIOC." [ref]
"Under this agreement, two operating companies were formed, one to explore for and produce oil and natural gas, and the other to refine part of this oil at Abadan Refinery on behalf of NIOC." [ref]
What then happened in 1979? Instigated unrest and armed insurrection, with western support (under the guise of "human rights"), leads to the toppling of the Iranian government and shortly afterwards takeover and formation of a backward Islamic regime. Obviously a strong and independent government in Iran did not serve the political/financial interests of these western powers/oil companies and a backward islamic state which they could deal with behind the scenes would be much more favorable to them.