Publications

East Java Basin is a proven Tertiary basin producing oil and gas. Oil and gas fill almost all the stratigraphy packages within the basin. Tectonic history of the basin has contributed significantly to hydrocarbon prospective and played a role in several processes, sediment distribution in the earliest basin filling processes, source rock maturation, trap generation, secondary porosity generation for limestone reservoirs, and migration pathways for connecting hydrocarbon kitchens to the reservoir sections during secondary migration. There are two main tectonic events in the basin. (1) Extensional tectonics as a result of basin stretching occurred during Paleogene to early Neogene time. (2) Regional rotation of Sundaland associated with tectonic push northward and westward from the Australian plate initiated compressional events in East Java. Compressional tectonics has resulted in structural and sedimentary products. The early sequence of Tuban formation is an initial product of sedimentation resulting from regional compressional tectonics in the Early Neogene within the basin. The evidence of compression in the Late Oligocene becomes critical to identify hydrocarbon accumulation in Pre-Kujung-1 reservoir. Rembang-Madura-Kangean-Sakala (RMKS) fault zone is the most familiar structural feature of the time and extends from Kangean to the north of East Java coastline in the Rembang area. RMKS fault zone aids in the formation of structural straps for hydrocarbon accumulation while the other compressional structural product provides migration pathways connecting kitchen to some traps in the region. The Pangkah and Sidayu fields are located to the north of RMKS fault zone. These fields have undergone several tectonic deformation events. Structural evidence within the area cannot be separated from the influence of RMKS fault zone. This paper will describe how compressional tectonics during the Neogene influenced structural configuration in Pangkah and Sidayu area and also how this impacted hydrocarbon perspectivity in the region.