The Pros and Cons of the Truncated Gaussian Method

The truncated gaussian method [6] [8] has been widely used in the past in order to simulate indicators. In this paper we investigate the potential and limitations of this method, from a geostatistical point of view and also from a practical one. First we present the method in detail including the hypotheses behind it. In particular we show that this method ensures consistency for the model in terms of the indicators variograms and cross variograms. Examples of the types of variograms that can and cannot be fitted using this method are presented. Then we discuss how to take into account vertical non stationarity for the indicators, as this seems to be the usual case (due to sequential evolutions in a sedimentary unit). This point will be illustrated via several examples. We then explain how the method can deal with a complex 3D non stationarity, and discuss the practical problems of using it in this case.