Incorporation of Uncertainty in Reservoir Engineering: A Data Management Problem
Authors: Rijnders J.P. 
Published: December 2007

This paper was prepared for the SPE-European Spring Meeting 1974 of the Society of Petroleum Engineers of AIME, held in Amsterdam, the Netherlands, May 29–30, 1974. Permission to copy is restricted to an abstract of not more than 300 words. Illustrations may not be copied. The abstract should contain conspicuous acknowledgment of where and by whom the paper is presented. Publication elsewhere after publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF publication in the JOURNAL OF PETROLEUM TECHNOLOGY or the SOCIETY OF PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor PETROLEUM ENGINEERS JOURNAL is usually granted upon request to the Editor of the appropriate journal provided agreement to give proper credit is made.

Discussion of this paper is invited. Three copies of any discussion should be sent to the Netherland Section of the Society of Petroleum Engineers, P. O. Box 228, The Hague, the Netherlands. Such discussion may be presented at the above meeting and, with the paper, may be considered for publication in one of the two SPE magazines.

The author deals with the data management aspects of incorporating uncertainty in reservoir engineering studies. A data base with supporting programmes which handles probabilistic estimates in a complex data probabilistic estimates in a complex data hierarchy, as used by NAM in The Netherlands, is described. Much attention has been paid to the systematic evaluation of the uncertainties associated with the basic data. Important factors in this respect are: The uncertainty associated with seismic information, determination of net reservoir rock and the areal influence of individual data points. This latter aspect is especially important when concluding initial studies with pertinent information from only a few control wells.

Introduction

The development of oil- and gas accumulations is always based on limited and uncertain data. Nevertheless decisions have to be made regardless of the uncertainties.

This is well recognized as is shown by many publications. Such work treats uncertainty generally in a more theoretical manner. It also stresses the importance of an analysis of uncertainty, as a first requirement for further application of the decision theory.

However, to date, decision theory has not generally been very successfully applied in Petroleum Engineering problems, except perhaps in some problem oriented cases. This perhaps in some problem oriented cases. This is surprising, since the Petroleum Industry is constantly faced with the evaluation of the consequences of these uncertainties and the application of the decision theory would seem to be beneficial. There are several reasons to explain why this is the case.

DECISION THEORY IN PETROLEUM ENGINEERING

As a result of the limitations of our thinking process, we have to work within the limits set by basic assumptions or working hypotheses. The problem is that we formulate or quantify uncertainties within the framework set by such concepts, but that it is nearly impossible to judge the uncertainty associated with a concept itself. This would require that we would be able to define (using the phraseology of the decision theory) all possible phraseology of the decision theory) all possible concepts, as a mutually exclusive and exhaustive list of all "states of the world"**. This is not possible except again perhaps in some isolated cases. The result is that our estimates are invariably of a conditional nature.