Reservoir Characterization using Simultaneous Inversion, AVO Analysis, and Seismic Attributes: A Case Study of Conglomerates-Volcanic, Northwest Java Basin

The Northwest Java Basin (NWJB) in Indonesia is a productive basin with proven oil and gas production. It consists of conglomerate, volcanic rock, and shale. A key exploration challenge in the NWJB is the extensive volcanic cover, which significantly reduces the effectiveness of conventional seismic methods. In this study, we employ seismic interpretation techniques to address these challenges and enhance the success of oil and gas exploration in volcanic-dominated settings. This study uses simultaneous inversion to characterize conglomerate distribution among volcanic rocks, using sensitive parameters like Vp/Vs, density, and lambda-rho. The study also uses AVO analysis on the LAC-12 well to identify potential locations. The study uses RMS amplitude, sweetness, and spectral decomposition attributes to support the structure at the study site. The simultaneous inversion was proven to characterize the distribution of conglomerate among volcanic rocks by using several sensitive parameters consisting of Vp/Vs with a cut-off value of <1.6, density with a cut-off value of <2.35 g/cc, and lambda-rho, or incompressibility, < 20 Gpa*g/cc. Furthermore, AVO analysis on the LAC-12 well showed that the reservoir in this study was of class IIp AVO type at the top and class II at the base. These attributes are integrated with the inversion parameter and supported by the interpretation of the AVO attribute cross-section, which produces three potential locations in the pre-TAF horizon with a depth of about 2100 ms.