Sealing and Non Sealing Faults of North Prospect Area in Jambi Merang Block, Jambi Sub Basin, South Sumatera



Jambi Merang Block is located within the northern edge of Jambi sub basin of the greater South Sumatra Basin. The block is bounded by Ketaling deep in the north-west and Merang Deep to the south- east . To the east the block is bounded by a basement high known as a SembilangHigh.The Jambi Merang Block is relatively a maturearea for exploration activities, however there are still several leads in the north- north eastern part of the block that need to be evaluated further;ie Padang Burung, Padang Pelawan and Cempedak. There are two major orientations of faults in the area which can be classified as early NW-SE trending strike-slip which produced NE-SW trending extensional fault system. Both faults were reactivated result of a younger convergent strike-slip.
These faults became an important factor in controlling trapping of hydrocarbon that might be migrated to the south east from the kitchen in the Ketaling Deep. As faults became a mayor controlling factor in trapping hydrocarbon mechanism in the North-north eastern area, a Fault seal analyses was conducted. The main purpose of the study is to evaluate and to characterize fault sealing capacity in relation to hydrocarbon migration, trap integrity and reservoir compartmentalization.
Fault Seal Analysis study indicates fault-sealing capacity varies in both vertical and lateral directions within the individual fault plane. Statistically, most faults in the study area are sealing types for Shale-Gouge-Ratio (SGR) cutoff 10% – 20% except for some location within TAF, Intra GUF and some ABF horizons. Most faults are leaking for SGR cutoff >30% particularly in the reservoir target structure. In this study, SGR calibration was not done due to limited available data in the area. SGR cutoff 15% was determined using average number from various fields in the world.
Based on the FSA results, fault sealing capacity is largely controlled by V-shale distributions rather than by throw as demonstrated by faults having small throws. This result suggested that distributions of good quality sand reservoir become the main control of fault sealing capacity.


Authors : Ardi Yoga Pradana, Moh Imron, Irma Kuswinda, Benyamin Sapiie