EVALUATION OF SEAL LAYER IN CARBONATE RESERVOIR AND IMPLICATION TO SURATMI SELATAN PROSPECT, SUNDA BASIN

• Main Author: Yudha Wikrama, Baskara
• Format: Theses
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/73113
• Institution: Institut Teknologi Bandung

Suratmi Selatan Prospect is part of Sunda Basin and located 3 km southward from nearest production field, Suratmi Field. Eventhough there is no oil accumulation in UBR sequence in this area, but evidence of oil trace and production profile plot shows this sequence could be act as reservoir. Various depths of LKO at Suratmi Field shows existence of seal layer that lies between GLM sequence and UBR sequence. This seal layer also presence between UBR sequence and LBR sequence, and opens the possibility of stratigraphic trap at Suratmi Selatan Prospect. Hence, this study is focused on analysis and distribution of seal layer lies between UBR and LBR sequence that has direct implication to the volume calculation. Core data description from this seal layer, porosity and permeability measurement from 358 samples, and log data were used as inital data to differentiate this seal layer from other units. This seal layer was identified as a mudstone, which is deposited at the base of every carbonate sequence and has wide distribution. Even the porosity has range up to 32%, but all of the sample only has permeability less than 10 mD, which exclude this layer to be a migration pathway of an oil in this area. From log data, this seal layer could be characterized by high gamma ray, low resistivity, and sharp contact with previous lithology. In this study, AI and LM ratio model from seismic inversion are the optimum way to see lateral distribution of this seal layer. Distribution of seal layer and boundary between UBR and LBR sequence could be seen from seismic inversion result. So the result of this study can prove the existing of seal layer that lies between UBR and LBR sequence, which create a stratigraphic trap at Suratmi Selatan Prospect. With this type of trap, volume of this prospect will be bigger than previous study which was calculated based on closure only.