This methodology refers to the present technological and economical situation predominating in the studied decades which means that it evaluates the economically exploitable oil in the present market concept. The cost limit established looks realistic since it is the one which would make competitive the different oil substitutes. The Petroconsultants' study does not care to project the evolution of discoveries. We have used the logistic fitting to the limit of 1800 Gb suggested by that study and compared it to the one shown in O C. Ferreira's study. Figure 3 shows the fitted data for the two hypothesis of total reserve.
Oil production is regulated to satisfy demand while stock variation is of little importance.
Therefore one may study together the evolution of both along the time. Figure 4 shows the evolution of world oil production. The strategic role of natural resources has been mocked by our authorities. Nevertheless, the developed countries demonstrated the importance of oil in their policies by reacting vigorously to Kuwait's aggression. On the other hand, they kept the nuclear option in spite of the environmentalists' opposition.