Publications

Hydrocarbon exploration and production efforts have been carried out in the Lower Kutai Basin, focusing on Mio-Pliocene reservoirs for more than a century. An estimated total of 5 BBL of oil and 60 TCF of gas resources have been discovered to date. The western area close to the basin margin or the so called ‘the Upper Kutai Basin’ is relatively under explored. The Medco Energi operated Kerendan Field is the first and the only Oligocene carbonate gas field in the basin. Exploration in the Upper Kutai Basin was initially focused on Paleogene Plays; the Eocene syn-rift and Oligocene carbonate plays. In contrast, the Miocene Play was not considered promising because the sediment was mainly eroded and exposed to the surface. Furthermore, the absence of any Lower Miocene commercial discoveries in the Kutai Basin puts a high exploration risk on any Lower Miocene Play target. The recent exploration in the Greater Bangkanai area has revealed a Lower Miocene potential. The reservoir of this play is older than the current producing sandstones in the fields to the east which are Late Miocene to Pliocene in age. The Kerendan development wells that penetrated the Miocene section, together with the new data from 2D seismic acquisition, Full Tensor Gravity (FTG) survey, surface geological mapping and microseepage geochemical analysis have significantly improved our understanding on Miocene Petroleum system. The prospective Miocene Play exists in the Kerendan Deep, a local depocentre in Bangkanai that has not suffered extensive uplift and erosion. The Miocene Play consist of Lower Miocene deltaic sandstones, with associated deltaic coals and carbonaceous shales. The potential reservoirs and source rocks are in places hence make a self-hydrocarbon sourcing system. The structural trapping mechanism is a 3-way dip closure on inverted thrust fault system that was covered by Lower Miocene intra-formational shales. A recent finding of a live oil seepage from an old coal well has directed our attention to an active Lower Miocene petroleum system. The results of an airborne FTG survey were integrated into the interpretation to complement limited and sparse 2D seismic and well data. The integrated study concluded that the NW-SE and W-E Lower Miocene delta system was developed in the southern margin of the Kutai Basin as shown by the Gross Depositional Environment (GDE) map. Petroleum system modeling suggests that the hydrocarbon expulsion occurred after the structural trap formation.. Furthermore, a fault seal study resulted in a high estimated SGR (shale gouge ratio) which may suggest that the fault trap is sealed. Despite a sparse and relatively poor quality existing 2D data set gives a relatively low confidence level on trap validity, all of other essential components for a working Miocene petroleum system are present in the Greater Bangkanai area. Therefore, further exploration program should be focused on confirming structural trap size and geometry to reduce the wide range of uncertainty.