Integrated Sedimentology Characters and Seismic Geomorphology for Reservoir Prediction of Tidal Shelf Ridge: The Upper Cibulakan Formation As A Shallow Marine Reservoir Analogue

The Upper Cibulakan Formation is one of the main reservoirs in the Offshore North West Java Basin. It was deposited in a shallow marine environment with Tidal Shelf Ridge morphology. Sedimentology and seismic approaches are integrated in this study to understand lithofacies, depositional stages and morphological patterns of Tidal Shelf Ridge. The study is restricted to Zone 29, P-Field with available data being 5 wells data that have cores, 64 well data, and 3D seismic data. The lithofacies data of these wells is integrated with log data using a Multi Resolution Graph-based Clustering (MRGC) method to predict the lithofacies and depositional stage of other wells without core. There are 10 different lithofacies and 4 facies association identified from these well cores. Facies associations that were found refer to nomenclature of depositional stage of Tidal Shelf Ridge. The embryonic stage consists of claystone-siltstone or calcareous highly-cemented sandstone (with erosional contact), which is the stage of beginning of deposition of the shelf ridge. The immature accretion stage consists of siltstone and sandstone with an intense heterolithic structure. The mature accretion stage consists of sandstone with little or no appearance of heterollitic structure. The abandonment stage is the final stage of shelf ridge that consist of calcareous highly-cemented sandstone without erosional contact. Stratigraphic pattern based on vertical order of facies association is showing 5 transgressive parasequence tracts bounded by 6 flooding surface markers. Based on seismic attributes, which is an average of amplitude x thickness in parasequence, the pattern and morphology of tidal shelf ridge body is relatively northeast – southwest direction. The results of this study are expected to be a reference in developing more advanced hydrocarbon production by understanding of the morphology of reservoir body.