In order to create realistic models of a reservoir with a vertical heterogeneity, it is often better to firstly divide it into several horizontal homogeneous geological units. The Vertical Proportion Curve (VPC) of wells extracted from the reservoir can illustrate the heterogeneity, but the choice of the geological units is usually based on a visual criterion. In the present paper, a new numerical method of wells VPC analysis is proposed. It consists in a geostatistical hierarchical clustering of VPC elementary intervals which results in the division of the reservoir into more homogeneous units that can be further used for modeling. The method is illustrated on two synthetic cases generated by the meandering channelized reservoir model Flumy and a real data case-study.