HYDROCARBON POTENTIAL OF UNEXPLORED TOKALA AREA IN THE EASTERN ARM SULAWESI AS PART OF AUSTRALIAN FRAGMENT: A PRELIMINARY RESULT

摘要

The study area is located in the southern part of onshore Matindok Block. This area is less explored than the northern part due to limited seismic data and undefined geological model. Exploration activities in the northern part started in 1996 and discovered several gas and condensate fields such as Matindok, Maleo Raja and Donggi Fields. Proven petroleum system plays for the northern part area are related to collisional tectonics between East Sulawesi Ophiolite (ESO) and Banggai-Sula block as part of Australian fragment. In 2016, Pertamina EP revisited geological model in the study area using mainly offshore 2D seismic and well data, gravity data, geological mapping report and published publications. The Preliminary result showed that there is possibility of new Australian fragment, which differs from Banggai-Sula block, and collided with ESO in the southern part of the area. The new geological model is based on Villeneuve et al. (2000) who discussed a two continental block collision in the eastern arm of Sulawesi, which are the Tokala and Banggai-Sula blocks. NW-SE 2D composite seismic line interpretation passes through Dongkala-1 and Tolo-I wells and showed the possibility of Tokala and Banggai-Sula Block sub-thrusted beneath ophiolite. Residual gravity anomaly also showed a new depocenter that differs from the proven kitchen area beneath Batui Thrust Mountain on northern part of the area. We have interpreted that Mesozoic sediments of Tokala Block are deposited in the new southern depocenter area. Based on previous geological mapping. Shale and Coal facies of the Triassic Tokala Fm. are defined as potential source rocks but its reservoir quality, trap integrity and seal effectiveness are not well defined. Finally, in 2017, Pertamina EP proposed geological mapping and petroleum system evaluation study to SKK MIGAS, in order to confirm the geological ? model and hydrocarbon potential of the Tokala and this has already been approved to be run in 2018. Hopefully, results of this study can trigger exploration activities in the Tokala area.