GEOLOGICAL STUDIES, RESERVOIR MODELLING AND HYDROCARBON RESERVES ESTIMATION, YADS FIELD, UPPER CIBULAKAN FORMATION, NORTH WEST JAVA BASIN

• Main Author: Auditio, Yesaya
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/79462
• Institution: Institut Teknologi Bandung

Yads Field administratively Yads Field is administratively located in West Java Province, North West Java Basin with an area of 30 km2. This field is located in a normal fault structure oriented north - south due to periods of compression deformation if we look at its regional geological structure. The North West Java Basin is one of the petroliferous basins located in the western part of Indonesia with hydrocarbons produced from several reservoirs such as siliciclastic, volcanic, and carbonate rocks with an age range from Eocene to Late Miocene. Cibulakan Formation acts as the main reservoir is the focus of the study. Reservoir modeling is also a way to find and find out how many reserves exist or are still left in a reservoir. The amount of existing reserves will determine subsequent exploration and development activities. By applying a stratigraphic sequence approach along with petrophysical analysis to determine the facies and depositional environment. When the geometry of the formation has been understood, reservoir zones are determined to estimate its hydrocarbon reserves. Seven well data from Yads Field, onshore Northwest Java Basin, were used that included well history reports, mud logs, wireline logs, checkshots, petrophysical data, and routine petrographic and core analysis. Two-dimensional seismic lines were also available with the study. This data is integrated for geological interpretation and reservoir modeling. The study showed that the Upper Cibulakan Formation in the study area consisted of carbonate rocks formed on shallow marine carbonate slopes. This carbonate interval can be further divided into three main facies namely carbonate reef, carbonate clastic, and marine shale with each facies having specific petrophysical characteristics. Thus, it is necessary to update previous estimates related to the volume available below the surface, in this case the Yads field. The reservoir in the Yads Field is the Upper Cibulakan Formation with a focus of research on the interval of the carbonate layer, namely Z-14. Based on the modeling of reservoir properties, the study area has an average v-shale value of 0.15, effective porosity of 0.056, water saturation of 0.78 with an average permeability of 62 mD and net to gross of 0.16. The estimated total volumetric hydrocarbons in the Yads Field are STOIIP 4 MMSTB and GIIP 4307 MMSCF.