This report examines the reasons why estimates of the size of oil fields tend to grow over time and the extent to which this may be expected to continue in the future. It looks at the causes of this phenomenon, the relative importance of these different causes, the methods available for forecasting future reserve growth and the validity of the assumptions used about reserve growth in an authoritative study of global oil resources.

This report examines the reasons why estimates of the size of oil fields tend to grow over time and the extent to which this may be expected to continue in the future. It looks at the causes of this phenomenon, the relative importance of these different causes, the methods available for forecasting future reserve growth and the validity of the assumptions used about reserve growth in an authoritative study of global oil resources. It concludes that reserve growth is of crucial importance for future global oil supply and is not primarily the result of conservative reporting.

This report forms part of the TPA’s assessment of evidence for near-term physical constraints on global oil supply. The assessment addresses the following question: 'What evidence is there to support the proposition that the global supply of ‘conventional oil’ will be constrained by physical depletion before 2030?