THE EFFECT OF CHANGE IN WATER LEVEL ON THE ABUNDANCE OF LIPTINITE AND VITRINITE MACERALS IN UPPER KELESA FORMATION SHALE IN KUBURAN PANJANG, RIAU

Abstract

Research on changes in water levels to the abundance of liptnite and vitrinite maceral has focused on Kuburan Panjang area of the Sumai sub-Basin, Central Sumatra Basin. The subject of this research is shale rock from the Eocene-Oligocene Kelesa Formation. Series of rocks from bottom to top shows repetition between shale, sandstone and mudstone strata bounded by conglomerates at the top and bottom. The composition of organic material consists of vitrinite ranging from 0.20 - 5.0%, liptinite 0.60 - 4.70%, pyrite 0.20 - 16.00%, carbonate maceral 0.20 - 24.2%, and clay mineral which is the most dominant component, ranging from 71.60 - 98.00%. Based on the results of TOC analysis, the abundant organic material of the Kelesa Formation shale has a TOC value of 1.18% to 7.17% indicating the ability of shale as a source rock is very good. The presence of organic material in the study area shows that there is a cycle of enrichment of organic material from bottom to top. The smaller the ratio of pristane/phytane (anoxic condition, high water level), the smaller the content of liptinite and the higher the content of vitrinite. Otherwise, the greater the ratio (oxic condition, low water level), the higher the content of liptinite and the lower the content of vitrinite. Change in water level during sedimentation has effect on the quality of shale as a source of unconventional hydrocarbon energy in the Kuburan Panjang area.