RESERVOIR CHARACTERIZATION OF BATURAJA FORMATION USING INTEGRATED METHODS OF PETROPHYSICAL EVALUATION, SEISMIC FACIES, AND INVERSION ANALYSIS IN VERA BASIN, OFFSHORE NORTHWEST JAVA.

Abstract

The Vera Basin is located in the Offshore Northwest Java area, the region is a known hydrocarbon province. This research is focused on to developing an understanding for the distribution of the Baturaja Formation. It involves looking into the potential depositional environments and in turn evaluate the reservoir properties within the Baturaja Formation. There are many ways to optimize the results of this research, including Geological and Geophysical approaches, including Petrophysical analysis, seismic interpretation and seismic inversion as it can provide information about subsurface conditions and the physical properties of rocks to reduce uncertainty from the reservoir distribution perspective. The project will discuss in detail the utilization of petrophysical analysis, seismic interpretation tied with the well log data, drilling cores, and other supporting data (geological data and drilling data) to characterize and evaluate the Batu Raja Formation. This research can be applied to understand the distribution of the Baturaja Formation and to evaluate the distribution of the reservoir properties in the Baturaja Formation. The results of petrophysical analysis and time structure mapping provide information that the depth of the Baturaja Formation in the study area ranges between 0.6 to 1.1 ms from the surface and the thickness of the formation is between 0.17 - 0.069 ms. Based on the results of model-based inversions along with the cross-plot analysis, the acoustic impedance (Zp) values ranges from 27500 - 30000 (ft / s) (g / cc) are classified as tight carbonates, that is carbonates with high density and very low porosity. Whereas, carbonates that have relatively high porosity are classified as porous carbonates with AI values from the inversion results ranging from 20000-27500 (ft / s) (g / cc) and shale having AI values below 20000 (ft / s) (g / cc). Seismic facies mapping based on amplitude extraction shows the characteristics of shallow marine deposits, the most likely gross depositional environment of the Baturaja Formation in the Vera Basin is rimmed shelf carbonates.