Publications

Paleogeography is a critical factor that typically receives less consideration by explorationists. Most of the consideration is usually focused on trapping mechanisms. Paleogeography is a guide to understanding both physical and chemical rock characteristics which correlate with their depositional environment. Integration of various geological and geophysical data will lead us to a better understanding of rock characteristics. In this study, a paleogeography model was generated by integrating several data sets, including structural evolution, stratigraphy, lithology, and biostratigraphy. Six paleogeography models of the East Java basin were created. These models are: Early Tertiary (P5-56-55Ma), Middle Eocene (P14-41Ma), Late Oligocene (P22-25.5Ma), Early Miocene (N7-16.5Ma), Middle Miocene (N9-14.5Ma), and Pleistocene (NN19-1.5Ma). In Middle Eocene times, there are many possibilities regarding the location of where the formation was deposited. Deposition would be controlled by the existence of local structural paleo-highs and horsts which were oriented in a NW-SE direction. Hydrocarbon generation occurred from about 15 Ma, and the depth of maturation window occurred at about 2,500 m. Given these assumptions, the possibility of source rock maturation is high, due to clastic sediments of the Ngimbang formation being deposited in a series of grabens that are presently below this burial depth. The Kujung reef definition is simplified and categorized as: 1) Reefal Paltform, 2) Pinnacle Reef, and 3) Isolated Reef. The Kujung Carbonates were deposited during the Early Miocene when a regional transgression occurred. The depositional environments were dominated by shallow marine littoral-sublittoral settings. The diagenetic process generally improved the reservoir quality of the Kujung Carbonate. Generally, the Kujung Carbonate shows fair to good reservoir quality, in range of 7-32% porosity, and 1-1400mD permeability.