ANALYSIS AND PREDICTION OF OVERPRESSURE CHARACTERISTIC IN ALSFIFAGETSU FIELD, EAST JAVA BASIN, EAST JAVA

• Main Author: Arga Dayen Siadari, Diasdo
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/33369
• Institution: Institut Teknologi Bandung

This study is located at Alsfifagetsu Field in the East Java Basin. The stratigraphy of the Madura PSC consists of Kujung II, Kujung I, Ngrayong, Wonocolo, Mundu, Paciran, and Lidah which are Early Oligocene to Pleistocene in age. The purposes of this study are to estimate pore pressure magnitude, determine the distribution of top of overpressure, analyse overpressure generating mechanism, and analyse the relationship between overpressure occurrence and geological condition in the study area. The analysis was performed in five offshore wells in Alsfifagetsu Field, by using wireline log (gamma ray, density, sonic, neutron, and resistivity log), pressure data, vitrinite reflectance data, and well report. Based on data processing and analysis, it is known that there is one well penetrating overpressure zone, i.e SDR-3.. The top of overpressure in SDR-3 is located at the depth of 3775 feet TVDSS with the magnitude of 2029 psi. Therefore, the analysis using Swarbrick’s method is needed to determine the distribution of top of overpressure in other wells. The main overpressure generating mechanism in the Alsfifagetsu Field is loading v mechanism, as observed from characteristics of wireline log and pore pressure profile through depth. The loading mechanism is caused by the high sedimentation rate ranging from 112–171 m/million years. The Swabrick’s method in other wells shows that the top of overpressure in other wells is still located under the total depth of the wells. Hydrocarbon has also started to form at the depth of 9000 feet TVDSS. Therefore, the hydrocarbon generation also contributes to overpressure development started at the depth of 9.000 feet down to the total depth of the wells