Abstract: Correctly delineating sedimentary microfacies provides guidance to the study of reservoir heterogeneity and distribution of reservoir parameters. However, traditionally the determination of the boundary of sedimentary microfacies largely relies on the researchers' experiences and thus tends to be subjective. In this work, the Sequential Indicator Simulation Method is used to solve the problem. With the method, equi- probabilistic models of distribution of microfacies in the plan can be obtained. When integrated with the experience of geological researchers, this approach not only demonstrates the variation of microfacies, but also minimizes the uncertainty of models due to the lack of data. Application of the method to the S2-2 layer in X oil field has shown satisfactory results.

Key words: sedimentary microfacies, reservoir boundary, stochastic simulation, geostatistics