CHARACTERISTIC OF CRUDE OILS IN MUSI PLATFORM, SOUTH PALEMBANG SUB-BASIN, SOUTH SUMATRA BASIN

Abstract

Musi Platform located in South Palembang Subbasin, South Sumatra Basin, bounded by Pigi Trough at the north, Saung Naga Graben at the south, and Benakat Gulley at the east. In Musi Platform, there are several oil fields that have been discovered and most of them remain produce oil to this day. Oil type variation discovered in the TG-1 – TG-13 – TG-10 – TG-4 - TG-7 - TG-5 – TG-2 – TG-11 wells. Location of their wells close to each other leads to assumption that they come from same kitchen. Oil analyses were conducted by geochemical analysis including liquid chromatography, gas chromatography, and gas chromatography-mass spectrometry analysis. Oil analysis included 21 samples for carbon isotope and 23 samples for biomarkers. Correlation of crude oil to crude oil, was done by interpreting carbon isotope and biomarkers data. Based on geochemical analysis of crude oil samples, using carbon isotope analysis, oils at research area could be divided into two groups: light saturates and heavy saturates. The light saturates were only found in TG-9, TG-8, TG-7, TG-10, and TG-13 wells, while another well contained heavy saturates. Furthermore, it can be concluded that there are three (3) oil families in the study area, i.e. lacustrine, lacustrine-estuarine, and shallow marine oil families. Lacustrine oil family show C₂₆/C₂₅ (tricyclic terpane) ratio is more than 1, ratio of C₃₁/C₃₀ hopane is smaller than 0.25, carbon isotope δ¹³C saturates value is -18.70 to -22.08, high C₂₈ sterane concentration, low diasterane concentration. Lacustrine-estuarine oil family show ratio of C₂₆/C₂₅ (tricyclic terpane) is more than 1, ratio of C₃₁/C₃₀ hopane is smaller than 0.25, value of carbon isotope δ¹³ C saturates -24.24 to -29.1, high C₂₉ sterane concentration, low diasterane concentration. Shallow marine oil family show ratio of C₂₆/C₂₅ (tricyclic terpane) is less than 1, C₃₁/C₃₀ hopane ratio is greater than 0.25, carbon isotope ¹³ C saturates value is -18.8 to -23.7, high C₂₇ sterane and diasterane concentration.