ABSTRACTThe quantitative method for ranking and scaling of biostratigraphic events has been being developed during the past 30 years. The purpose is to combine biostratigraphic dataform exploratory wells drilled in sedimentary basins to construct a regional biozonation that can be used for correlation between sections within a study area. Ranking is illustrated by application to a simple, artificial dataset. Scaling is explained as a refinement of ranking. Implications of sampling of stratigraphic sections are discussed in detail. In this paper used data of Central Sumatra Basin wellbore for example. The results of scaling analysis are 43 biostratigraphic events and 8 biozonation which characterized by last occurrence of optimum events, while the ranking analysis resulted Optimum sequence of probable depth each event of wells. The correlation used Globi erinoides obliguus obliggus as indexfossil.