Publications

Biostratigraphic analyses, well logs, seismic and core data have been reviewed and integrated with public domain information to refine and update the regional tectono-stratigraphic model for the South Makassar Basin. This study has recognised four regionally significant mega-sequences within the Middle Eocene to Middle Miocene, from oldest to youngest: SMB-I, SMB-II, SMB-III and SMB-IV, which reflect the complex interplay between tectonic and eustatic sea level controls on regional sediment type and distribution. The first phase of extension during the Middle Eocene (SMB-I), approximately 45-37mya, resulted in the development of a series of localized half-grabens with a predominant NW-SE orientation, such as the Pangkat-1 area where fluvio-lacustrine sediments were deposited within two half-grabens. Pangkat-1 and Taka Talu-1 provide direct evidence for source and reservoir lithologies, respectively. A second, more widespread, phase of extension during the Late Eocene to Early Oligocene (SMBII), 37-28mya (possibly to 20mya), is evidenced by the development of the NNE-SSW trending Taka Talu Graben, where thick and long-lived breccias were deposited adjacent to faults (Taka Talu-1). The fault orientation and timing of initiation are consistent with literature studies regarding the opening of the South Makassar Basin, although faulting may have continued later than has previously been documented. A series of major transgressions during this time resulted in extensive marine sedimentation, ranging from bathyal claystones in the Pangkat Graben to shallow water * Mubadala Petroleum, Jakarta, Indonesia ** Mubadala petroleum, Kuala Lumpur, Malaysia carbonates on the Paternoster Platform and at Sultan-1. A significant drop in relative sea-level is noted at the beginning of the Early Oligocene. This time (SMB-III), 28-20mya, was a period of both global second-order eustatic lowstand and regional thirdorder eustatic lowstand. Carbonate platform deposits were eroded from the Paternoster Platform and re-deposited in bathyal waters of the Pangkat Graben as debris flows. This includes the gasbearing reservoir at the Ruby Field. A second major lowstand occurred from Early to Middle Miocene (SMB-IV), 20-12mya, which coincided with the demise of carbonates in the area. Seismic mapping and biostratigraphic data indicate that pro-delta sediments prograded from NW to SE, filling the Pangkat Graben, backstepping onto the Paternoster platform, and prograding into the South Makassar Basin. These shales act as regional seals for the area.