ANALISIS KARAKTERISTIK OVERPRESSEURE DI LAPANGAN JAMBI, SUB CEKUNGAN JAMBI, CEKUNGAN SUMATERA SELATAN

• Main Author: Nurizakiyah, Salma
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/74284
• Institution: Institut Teknologi Bandung

<p align="justify"> Jambi Field, Jambi Sub-Basin, South Sumatra Basin is one of the hydrocarbon-producing fields in Indonesia. This basin is known to have overpressure zones. Pore pressure analysis is needed to avoid risks due to overpressure such as blowout and kick. The objective of this study are to determine the depth of the first occurrence of overpressure, estimate pore pressure using wireline log data, determine the mechanism of overpressure generation, and analyze the relationship between overpressure occurrence and clay mineral diagenesis, hydrocarbon generation, and rate of sedimentation. This study was conducted on six wells, i.e NAG-1, NAG-2, TS-1, TS-2, NTC-1, and NTC-2 using wireline log, temperature, mud weight, pressure test, drilling report, vitrinite reflectance, and XRD data by using the Eaton Method. The first occurrence of overpressure in NAG-1, NAG-2, TS-1, NTC-1, and NTC-2 Wells are, respectively at -1955, -1946, -1861, -1840, -981, and -1010 mTVDSS which is equivalent to the Gumai Formation. The estimated pore pressure gradient ranges from 0.45 – 0.85 psi/ft. The mechanism of overpressure generation in NAG-1 and NAG-2 wells are non-loading. Whereas in TS-1, TS-2, NTC-1, and NTC-2 wells are loading. Overpressure with the non-loading mechanism is generated by clay mineral diagenesis due to the shale-dominated sequence of the Gumai Formation and hydrocarbon generation owing by good TOC and mature hydrocarbons in the Gumai Formation. In comparison, the loading mechanism is generated by continuous loading as a result of the rapid sedimentation of the Gumai Formation. The variations in the depth of the first occurrence of overpressure might be due to erosion in the anticline that took place during the syn-orogeny phase.