The post-1950s concessions are significantly different with respect to ownership of hydrocarbons. The state has permanent sovereignty over the hydrocarbons within its territory and the concessions grant an IOC a legal title to the hydrocarbons, but only once recovered at the well-head. As with licences, the concessionaires have propriety rights over the concession areas. In addition, the modern concessions are for shorter periods of time and the concession areas are limited to smaller geographical areas that may be required to be relinquished depending on the work programme and budget. The IOC takes most of the exploration risks and the state generally derives all its revenues from royalties, income taxes and other similar payments.
– Geoffrey Picton-Turbervill (ed), Oil and gas: a practical handbook (Globe Law and Business, 2009), p33.