THE ANALYSIS OF OVERPRESSURE CHARACTERISTIC IN CGK FIELD, TARAKAN BASIN, NORTH KALIMANTAN

• Main Author: Naufal Irnanda, Prayudha
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/29976
• Institution: Institut Teknologi Bandung

<p align="justify">The study area is located in the CGK Field, Tarakan Basin, North Kalimantan. The stratigraphy of the CGK Field is divided into four formations, i.e. Tarakan, Tabul, Meliat, and Naintupo. The study is performed in these four formations which are Early Miocene – Pliocene in age. <br /> <br /> The purpose of this study is to estimate pore pressure, determine top of overpressure, analyse overpressure generating mechanism, and analyse the relationship between overpressure and geological condition in the study area. The analyses were performed in 4 wells by using wireline log data, mudlog data, formation pressure, temperature, well report, and vitrinite reflectance. <br /> <br /> The characteristic of overpressure is observed from the profile of stress/pressure and response of wireline log through depth. The result of the analysis shows that two out of four wells penetrate overpressure zone. The top of overpressure ranges from 4840-7000 ft TVDSS, with the magnitude of overpressure around 2600-6011 psi. The overpressure generating mechanism is loading and non-loading mechanisms. The loading mechanism is caused by high rate of sedimentation, in the range of 101-560 m/million year. The overpressure characteristic in the study area is also marked by deflections in sonic and resistivity logs at top of overpressure indicating non-loading mechanism. The vitrinite reflectance data suggest that the mechanism responsible for the non-loading process is kerogen – hydrocarbon transformation. However, there is a possibility of limited contribution from clay diagenesis to the non-loading mechanism. <p align="justify">