Perpustakaan Digital ITB

The Northeast Java Basin is mostly offshore basin situated in the back arc basin and located in western Indonesia. It can be separated into three main parts, namely, Northern Platform, Central High, and Southern Basin. The main objectives of this research are to determine the type of facies, environments and petrophysical properties of Eocene clastic of Ngimbang Formation and to use them for both facies and petrophysical modeling. The purpose of this study is to evaluate the relationship between depositional facies, structural and petrophysical modeling to generate a good understanding model in clastic reservoir. The data availability of this study are based on well logs data and 2D seismic data, and secondary data such as cutting descriptions, sidewall cores, and regional study were used as supporting in this study. Based on the stratigraphy and facies sedimentation; the stratigraphic correlation from northwest to southeast direction, the formations intervals are divided into four zones bounded by flooding surface as a marker of sequence stratigraphic. The depositional facies analysis was carried out using electrofacies analysis, which is then used as a reference in the well correlation. In this study, the electrofacies have been defined by gamma-ray log pattern. This study concluded these electrofacies consisted of fluvial channel blocky shaped, flood plain serrated shaped, crevasse splay funnel shaped, coal, distributary channel bell shaped (fining upward), distributary mouth bar funnel shaped (coarsening upward), lacustrine shale, marine shale, shoreline sandstone funnel shaped and carbonate lithology. From the 2D seismic interpretation, concluded that there are five faults in the form of normal faults and all of them have northeast-southwest trend. The fluvial channel direction come from northwest direction and going to the southeast direction to the marine area. According to the electrofacies analysis and geological final well report, can concluded that the depositional environment of Eocene clastic of Ngimbang Formation in the study area is fluvial-deltic, lacustrine and marine environment, comprising from interbedded of sandstones, shales, with some coals. The isopach map of Eocene clastic of Ngimbang Formation concluded that the southeast area is thicker than the northwest area, and the depth structural map concluded that the northwest area is higher than the southeast area. The depositional direction of Eocene clastic of Ngimbang Formation in the study is north-south and deposited at low and thick area in graben structural has trend E-W in the east of study area. The petrophysical modeling concluded that the low volume of shale, high porosity and low water saturation in the northwest of study area.