The dispute between ‘optimists’ and ‘pessimists’ over the future of global oil supply is underpinned by equally polarised disagreements over a set of more technical issues. Given the complexity and multi-dimensional nature of this topic, the existence of such disagreements is unsurprising. However, the situation is made worse by the inadequacy of the publicly available data and the scope this creates for competing views and interpretations. Improved data on individual fields could go a long way towards resolving such disagreements, but this seems unlikely to become available in the foreseeable future. Nevertheless, there is potential for increasing the degree of consensus in a number of areas and some progress has already been made. This report looks in more detail at two of these issues, namely:
- Decline rates: how rapidly the production from different categories of field is declining and how this may be expected to change in the future.
- Depletion rates: how rapidly the remaining resources in a field or region can be produced.
Section 2 summarises the causes of production decline and introduces some simple empirical equations to model decline. Section 3 provides some illustrative examples of production decline at both the field and regional level and shows how decline ratescan vary with the size and age of fields. Section 4 summarises the results of three studies that seek to estimate the global average rate of decline of post-peak oil fields and to forecast how this may change in the future. This variable is of critical importance for future global oil supply. Section 5 examines the related concept of depletion rates, including the available estimates of the rate of depletion the different
typesof field and the importance of this variable for global supply forecasts. Section 6 concludes.