Jabung Field occupied in Sub Jambi Basin represents northern flank of South Sumatra Basin. The South Sumatra Basin is one of the most hydrocarbon prolific Indonesian Tertiary back-arc basins. The study area is dominated by NW-SE and NE-SW trending basement structures. Both of structural trends controlled the major field distribution in the district. South Sumatra Basin was formed as pull-apart basin related to NW-SE trending dextral strike-slip faults. This paper discuss the results of integrated study of 3D fault frameworks, balancing cross-section, analogue sandbox modeling and faults seal analysis as part of structural geology evaluation in the Jabung field which concentrate in finding and determining kinematics relationship among different faulting events. 2D and 3D Seismic interpretations were concentrated in recognizing structural pattern and kinematics. Based on palinspatic models made from 2D seismic indicates deformation in Jabung Block show a group of contrasting strain features: early extensional faults forming the syn-rift deposit following by inversion structures and cross-cut by latter extensional structural style. The strain axes consistently show maximum NW-SE direction of extension and NNE-SSW direction of shortening. Therefore, it concluded that both structures (extensional and shortening) were formed during continuous strike-slip deformation. This model has been verified and simulated using analogue sandbox modeling. Pre-existing basement fractures and their geometry acted as major control to the structures development in the Jabung Field particularly graben formation. Fault seal characteristic based on SGR indicates that most of the faults in Jabung Field are sealing type (as barrier for fluid across fault) except in relatively small area where faults oriented forty five degree to the present-day maximum horizontal stress (Shmax).
Author : Zaenal Holis, Benyamin Sapiie, I Nyoman Suta, Moh. Kusuma Utama, Meli Hadiana