ANALYSIS CARBONATES RESERVOIROF KUJUNG I FORMATION LIMESTONESIN BUNDA FIELD, MADURA STRAIT EAST JAVA BASIN

• Main Author: HAN , KIAN
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/16230
• Institution: Institut Teknologi Bandung

Limestones of Kujung I Formation in Bunda field, East Java Basin was interpreted as carbonate buildup grown on isolated platform with WSW-ESE trend. This limestones growth fast to catch up with the rising of sealevel during Early Miocene. This carbonates deposition started with start up phase, catch up, keep up and finally give up. After that the production of carbonates in this reefal limestones of Kujung I was stop growing due to exposure. Core laboratory analysis result shows the carbonates reservoir of Kujung I limestones near crestal of the carbonate buildup has good porosity and permeability, but if this reefal limestone was cemented by phosphate hence the rock permeability could be reduced. Reefal limestone cemented by phosphate is also known as phosphatic guano that interpreted as a result of accumulation from bird’s secretion which been dissolved and reacted with limestones by fresh water and formed phosphatic cement. Phosphatic guano layers weredeveloped and interpreted as a result of surface exposure due to sealevel changes during carbonates deposition. The understanding of depositional process of Kujung I Formation limestones was based on core analysis report, wireline log analysis and 3D seismic interpretation. This integrated study then will help in correlating two exploration wells in Bunda field. Seismic horizon flattening and proportional slice will assist in evaluating the depositional process and to know the lateral distribution of carbonates reservoir of Kujung I Formation limestones in Bunda field. Isochron time thickness mapping and IST (Integrated Seismic Trace)attribute analysis were used to know the reservoir geometry and lateral distribution of reefal limestones and phosphatic guano layers. Phosphatic guano layer tends to be distributed locally and discontinued. Result of this research is expected could assist in the optimization of Bunda field development particularly to determine the depth of targeted reservoir in the horizontal development wells. The horizontal development well is suggested not to penetrate the phosphatic guano layer which has relatively lower permeability.