OVERPRESSURE ANALYSIS AND PORE PRESSURE PREDICTION OF EAST JAVA OFFSHORE AREA-MADURA SUBBASIN

• Main Author: RISNANDAR SINULINGGA (NIM:22013312), YUDHA
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/31798
• Institution: Institut Teknologi Bandung

The East Java Basin is renowned as one of the prolific Tertiary hydrocarbon basin. This basin is also well known for its overpressure characteristics which occurs as a problem in drilling activity. Ovepressure in East Java Basin generally occurs in Plio-Pleistocene interval which is deposited in depression by rapid sedimentation rate. <br /> <br /> Wireline logs, pressure direct measurements, drilling mudweight and drilling events from four offshore exploration wells of PHE WMO are analysed to study overpressure characteristics and its mechanism. Eaton’s and Swarbrick’s Method are used to estimate the magnitude of pore pressure in research area. <br /> <br /> Disequilibrium compaction is the main overpressure generating mechanism in the study area. The depth of overpressure vary in study area, ranging from 700 feet to 2,200 below seabed. Uplifting followed by erosion process are suspected as main factor of top overpressure depth variation in study area. <br /> <br /> Pore pressure prediction was conducted using Eaton’s and Swarbrick’s Method. 0.8-1.2 Eaton’s exponent number shows a good match to direct pressure measurement and mud weight data from wells. The depth of overpressure which has been identified by Eaton’s is still within range of top Fluid Retention Depth (FRD) by Swarbrick’s except for one well. <br /> <br /> Source rock geochemistry analysis shows there is no relationship between source rock maturation process with ovepressure generating mechanism in study area. This fact is based on vitrinite reflectance and Tmax data that shows the organic material will enter maturation window at depth more than 12,000 feet.