Biostratigraphic analysis based on planktic Foraminifera from well X in North Sumatra Basin

Abstract

There have been several studies conducted in the North Sumatra Basin, but there is a scanty information related to the age of the Formations in the basin. The aim of this study is to establish the age of the Formation. A total of 128 ditch cutting samples are used for lithostratigraphy analysis, in which 33 samples were analysed further for the Foraminifera biostratigraphy study from the well X at a depth of 6090 – 9919 feet. From the result of the analysis, 38 species from 16 genera successfully identified, as well as 5 datum species, namely FO Globigerinoides sicanus, FO Orbulina suturalis, FO Globorotalia menardii, FO Globorotalia plesiotumida and FO Globorotalia tumida. From the lithology data, three (3) lithostratigraphic unit successfully identified, namely the calcareous claystone, very fine calcareous sandstone and fine calcareous sandstone unit which is estimated to be comparable to the Baong, Keutapang and Seurula Formation. From the result of the study it’s concluded that the lithostratigraphic units found in the study area have the age range of N7-N18 or the late Early Miocene to the Late Miocene.