ANALYSIS OF OVERPRESSURE CHARACTERISTICS USING WIRE LOG DATA IN THE SOUTH PALEMBANG SUB-BASIN, SOUTH SUMATRA BASIN

• Main Author: Hariyuna Yomandha, Galih
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/69692
• Institution: Institut Teknologi Bandung

The South Sumatra Basin is one of the exploration basins in Indonesia which is dominated by shale lithology (impermeable), so it tends to form a closed system where the fluid in the rock pores cannot escape. This is one of the "ideal" conditions for the formation of an overpressured zone. Pore pressure analysis becomes important to minimize drilling risks, such as loss, kick, and blowout. This has a significant negative impact on operational and financial activities. Therefore, the purpose of this study is to determine the depth zone and the mechanism of overpressure formation, to analyze the relationship of the overpressured zone to its geological conditions, and to estimate the value of the pore pressure in the overpressured zone. This research was conducted in the XR-1 well (Benakat Valley) and XB-1 well (Banteng High) using wire line log data, temperature, mud weight, pressure test, and drilling reports. The overpressured zone corresponds to the Gumai Formation at depth intervals of 1675-3207 meters (XR-1) and 2204-3349 meters (XB-1) caused by loading (XR-1) and non-loading (XB-1) mechanisms. The loading mechanism is the result of fast sediment loading, while non-loading is the result of the transformation of smectite into illite. The pore pressure values range from 2528-4438 psi (XR-1) and 3349-5312 psi (XB-1).