Since 1951, National Iranian Oil Company (NIOC) has been directing and making policies for exploration, drilling, production, research and development, refining, distribution and export of oil, gas, petroleum products. NIOC, with a vast amount of oil and gas resources, is one of the world’s largest oil companies. At the present time, it is estimated that the company holds 156.53 billion barrels of liquid hydrocarbons and 33.79 trillion cubic meters of natural gas. NIOC consists of 17 production companies, 8 technical service companies, 7 managements, 6 divisions (administrative units) and 5 organizational units.