Comparing Facies Realizations – Defining Metrices on Realization Space

A typical workflow for generating flow simulation grids goes through a facies modelling step. This typically involves setting up a stochastic model that is supposed to capture the important properties of the facies bodies in the reservoir volume in question and their uncertainties. This may be difficult or impossible within a particular modelling framework. Either we end up with a model too simple to be able to reproduce the characteristics of the reservoir, or the model parametres become too many and too difficult to specify. Hence users ask for methods able to reproduce the properties of a training image automatically. In any case one would like objective measures of similarity of facies realizations so that one is able to determine if a set of realizations have the properties that one wants.<br><br>Here we discuss possible components in a metric on a space of facies realizations and present an implementation of a facies realization analyzer program. The algorithm simply scans a number of realizations and computes the global volume fractions of each facies and the number of facies bodies of each type. Then it computes the surface areas, volumes, and extensions in each directions for the bodies and performs simple statistical analysis of the realizations and compare it with properties of a training image.<br><br>We present results of applying this software on facies realizations produced with variogram based methods, multipoint methods, and sequential Markov random fields.<br><br>The analyzer algorithm is fast, applicable in 2D and 3D, and the results are in excellent agreement with the subjective impression of similarity or dissimilarity obtained through visual inspection.<br><br>