ABSTRACTS
 2nd International Workshop on Oil Depletion
Paris, France, May 26-27 2003
Organised by the Association for the Study of Peak Oil and Gas
The workshop was held at the  Institut Francais du Pétrole , Rueil Malmaison, Paris.

  Proceedings of the 2nd International Workshop on Oil Depletion, Paris, France, May 26-27 2003,
Edited by K. Aleklett, C. Campbell and J. Meyer, www.peakoil.net/iwood2003 .

Modelling of Remaining Reserves in a Mature Basin Dr. Vincent Lepez The speech will present results and possible extensions of a PhD research.  The aim of this work is to build a statistical model of oil and gas fields' sizes distribution in a given petroleum system, for both the fields that exist in the subsoil and those which have already been discovered. The estimation of the parameters of the model via some innovative statistical tools helps to provide estimates of the total number of fields which are yet to be discovered, by class of size. Following some previous work by Laherrère, we assume that the set of underground fields' sizes is a sample of unknown population with Lévy-Pareto law, which parameter is unknown.  We also assume that the area is mature enough to ensure that the biggest field has been discovered for sure.  The set of already discovered fields is a sub-sample without replacement of the latter which is "size-biased", due to the effectiveness of geologists' work!  Indeed, the bigger a field, the larger its probability of having been discovered.  But how large?  This is the question we shall try answer. An arbitrary partition of the observed sizes' interval being set (called a model), we are able to estimate the inclusion probability of a given class, defined as the ratio between the number of fields discovered in the class and their total number in the subsoil.  This information allows one to derive within-class and total estimates of the number of fields and reserves that are yet to discovered. We then allow our partitions to vary inside several families of models and prove a model selection theorem, which aims at selecting the best possible partition in terms of a statistical quality criterion. We conclude with various applications to real data and propose a discussion of the underlying hypotheses of this work and possible extensions regarding, for instance, the influence of technological progress, better geoscience knowledge or economical impacts through time.  Another crucial matter that will be discussed is the associated possible forecast of the aggregated production profile of these new reserves. Back to Proceedings