--> Form and Fill of Rift Basins Along Strike-Slip Fault Systems: Lower Talangakar Formation, Jatibarang Subbasin, Offshore NW Java, Indonesia

AAPG ACE 2018

Datapages, Inc.Print this page

Form and Fill of Rift Basins Along Strike-Slip Fault Systems: Lower Talangakar Formation, Jatibarang Subbasin, Offshore NW Java, Indonesia

Abstract

Jatibarang sub-basin, located in eastern offshore northwest Java Basin, has been considered a proven hydrocarbon basin in an extensional, strike-slip rift setting. Over the past 35 years exploration success has been mixed, with much focus on exploring proximal to the rift-bounding faults, but with limited attention to other significant elements of this basin. Little consideration has been given to temporal changes in source basin variability, and the role of secondary faulting in reservoir sediment routing. This research employs a broader investigation of these aforementioned issues using an extensive database: 22 wells, 710ft of core, mud logs, sidewall core, palynology-biostratigraphy data, 850 km2 3D seismic cube and 36 2D seismic lines to understand the relationship between structural evolution and sediment distribution in the basin with a goal to impact future opportunities in this and other strike-slip associated rift basins.

Core analysis indicates that depositional environments include river systems both meandering and braided, alluvial fans, fan deltas and shelf lacustrine systems. Six stratigraphic sequences are defined in wells and seismic, supported by biostratigraphic data. These sequences are furthermore divided into genetic sequence sets and the resultant framework used to understand accommodation changes. Regional stresses controlled the migration of lacustrine source-rock depocenters, and were influenced by the formation of the first secondary fault splay in Early Oligocene, followed by the initiation of the second secondary fault splay in the Late Oligocene. These secondary faults form major sediment linkages between the sediment sourcing areas of the rift-bounding faults to the north and the sinks forming to the south. Results of this study reveal the follow key observations 1) there is a strong link between strike-slip secondary fault splays and sedimentation pathways, because of this genetic relationship we see (2) development of alluvial fans and fan deltas distributed spatially and continuously proximal to the rift bordering strike slip fault, (3) major sediment entrance points are developed where border faults link with secondary fault splays. (4) Secondary faults confine braided fluvial systems (BFS) to their downthrown block resulting in BFS extending basinward in trends paralleling these splays, (4) deep basin sinks migrate in association with development of secondary splay faults and are dominated by subaqueous fan deposition.