Due to the critical importance of oil to modern economic activity, and oil's non-renewable nature, it is extremely important to try to estimate possible trajectories of future oil production while accounting for uncertainties in resource estimates and demand growth, and other factors that might limit production. In this study, we develop several alternate future scenarios for conventional oil supply, given the current range of the estimates of resource availability and of future demand, and assuming that production will continue to increase unconstrained by political or economic factors such as deliberate withholdings; or prolonged global recession. Our results predict that global production of conventional oil will almost certainly begin an irreversible decline somewhere between 2004 and 2037, at 22 to 42 billion barrels per year, depending upon how much oil is available from the earth's crust and the growth rate in its use. In addition, we found that the increasing domestic use of conventional oil in oil-producing countries is very likely to eliminate over time the ability of these countries to export oil to net-consumer countries, so that the number of net-exporting countries will be reduced from 35 today to between 12 and 28 by 2030, and fewer subsequently. The geopolitical and economic implications of these trends are likely to be pronounced if reliance on cheap oil is not reduced prior to the peak. (C) 2004 Elsevier Ltd. All rights reserved.