Abstract: Study of reservoir heterogeneity is significant for reservoir characterization. The parameter space distribution is not only of randomness, but of structural feature. From the basic principle of the variogram in geostatistics, this paper presents a mathematical model for quantitatively characterizing horizontal heterogeneity in reservoir. The case estimated results of using individual sand thickness as regional variables from various types of reservoirs in a field showed that the horizontal heterogeneities in different types of reservoirs fit the basic patterns in sedimentation,and this characterized model can be applied in them. In addition,compared to variable coefficient estimates,this method is superior to the available traditional mathematical statistics approaches.

Key words: reservoir rock, heterogeneity, variable, randomness, variable function