INTEGRATED PORE PRESSURE MODEL ESTIMATION STUDY CASE :JAMBI SUB-BASIN, SOUTH SUMATRA

• Main Author: Farhan Farabi A, Ahmad
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/51693
• Institution: Institut Teknologi Bandung

Pore pressure estimation is needed in drilling wells for safety purposes and it is also a very effective method for dealing with drilling accidents. Determination of overpressure is the main foundation in the evaluation to minimize the non-productive time (NPT). The purpose of this study is to integrate the pore pressure model with well data and seismic velocity data for the purposes of evaluation in the vertical and lateral continuity. Here we present several models to generate pore pressure analysis from well and seismic velocity data of Jambi Sub-basin, South Sumatera, Indonesia. Those methods will be compared to gain more accurate model estimation within the study area. Kan and Swan’s model show the best fit for estimation on a higher frequency which validated by formation tester with parameter of C1 = 0.001 and C2 = 0.0003 in Jambi Sub-basin. The velocity data to construct the 3D pore pressure model was also validated with well data using multi-attribute analysis. The multi-attribute analysis here used 2 algorithms, namely step-wise regression and probabilistic neural network (PNN). The analysis shows that PNN has a better correlation about 0.96 and the average error is 154.99 compared to step-wise regression. This analysis shows that the overpressure zone starts at 1700 – 2400 meters around interval Gumai Formation which contain pressure up to 6500 psi or equivalent to 0.8 psi/ft. The overpressure dominated by Gumai and Talang Akar Formation is caused by loading mechanism which have a transgression stage dominated by thick shale sequence which caused the rate of sedimentation is higher than the rate of dewatering on deep marine deposition at the age late Oligocene - early Miocene.