Publications

The Talang Akar Formation was deposited in the syn-rift scheme of the tectonic setting in periods of Eocene to Oligocene that formed rifts or half-graben complexes along most of the southern edge of the Sunda Shelf plate (now Sumatra and Northwest Java). Originally, the Talang Akar Formation had fluvio-deltaic until marine facies, which were filled by sandstone interbedded with non-marine shale at the start of the deposit and limestone interbedded with shale at the end of deposit. Elastic Impedance (EI) inversion and Lamda Mu Rho (LMR) inversion methods have been applied in this study to identify the distribution, geometry, and hydrocarbon content of the Talang Akar sandstone. The process of EI Inversion at angle 28° is proven the most sensitive in mapping lithology and fluids while the LMR inversion method is used to correlate the results of the hydrocarbon anomalies in the EI inversion method. AVO attributes indicate the targeted layer z.2260 as a class IV AVO anomaly, inferring low impedance sands. The EI inversion at angle 28° shows its EI value ranges between 10000–12600 ((m/s)2*(gr/cc)) with well-developed sandstone reservoirs in some areas. The sandstone reservoir in the area around the well DONAT-08 is well developed, but well DONAT-10 is dominated by shale. Hydrocarbon anomalies can be subdivided into three zones: southwestern, northwestern, and southeastern parts of the “JOGGING” field. The hydrocarbon anomaly distribution in the first zone based on the LMR inversion isn’t necessarily in line with the EI 28° inversion (west- to-east trend), while the second and third zones show consistency (north-to-south trend). Based on the inversion results, hydrocarbon anomalies are trapped throughout the hinge and flank of the anticlinal structure.