Publications

The geology of the Metaweja area is characterized by the turbidite sequence which are deposited in the deep-sea environment during the Miocene and exposed to surface due to the latest deformation. The research was conducted to identify the potential source rock and reservoir rock within the turbidite deposits. In the study area, there are three types of rock units, calcareous shale units formed in the Late Miocene, Sandstone unit and interbedded siltstone-sandstone unit that were deposited in Middle Miocene. Measured section was carried out at the several stations in order to analyze the turbid current deposition mechanism. Measured section of the alternating unit of sandstone - siltstone are observed at several places where the unit has intercalation of shale, coal and iron oxide. Some syn-depositional sedimentary structure also found within this unit. The carbonate shale unit has good total organic content (TOC) ranging from 0.51wt% to 2.56wt%. Pyrolysis analysis has S2 value 1.31 mg/g to 1.34 mg/g, Hydrogen Index (HI) 35 mgHC/g to 49 mgHC/g, Oxygen Index (OI) 35 mgHC/g to 49 mgHC/g, Tmax 430 °C to 434 °C and Vitrinite Reflecteance index (Ro) 0.32% to 0.54%. The carbonate shale characterized as the type III kerogen which prone gas source rock and interpreted as immature to early mature source rock. The petrography analysis of alternating rocks of sandstone - siltstone has characteristics of sandstones with 44% of volcanic lithic fragment composition, 20% matrix 10% clay size fragments, secondary porosity reaches 10% and 13% cement carbonate calcite. Based on the petrography analysis, this unit could be interpreted as reservoir rock, although we need further analysis for the Permeability measurement.