SHALE GAS POTENTIAL OF LOWER BAONG FORMATION NORTH SUMATRA BASIN : A CASE STUDY OF UNCONVENTIONAL ENERGY

摘要

North Sumatra basin is a back arc basin created from Hindia-Australia subduction Oligocene - Late Eocene. Its Middle Miocene thick shale Lower Baong Formation contains high organic matter. This study emphasizes on shale gas potential of Baong Formation. The data in this study area use sample of shale rock, seismic, and geological map. Analysis of petrography, SEM, XRD, and geochemistry has been done to obtain shale gas characterization. Petrography, SEM and XRD analysis show that Baong Formation is characterized by shale that contains high clay mineral such as smectite illite and kaolinite, carbonate minerals such as calcite and siderite and less of quartz, pyrite, feldspar, and plagioclase. Geochemistry analysis of Lower Baong Formation show high Total Organic Contain, 0.63 - 1.4%. The maturity level of shale show near mature (Tmaz 426 - 437O), HI value of shale is 81 - 146 mg HC/g, and kerogen type of this formation is type II/III. Kerogen composition of shale sample commonly shows vitrinitic kerogen. The hystorical maturity model has helped to explain gas window in Lower Baong Formation. The calculation of shale gas in Lower Baong Formation, using Jarvie and Lewis equation shows the volume of shale, absorbed gas and free gas. Analysis and interpretation show that shale of Lower Baong Formation of North Sumatra Basin has shale gas potential.