Publications

A recent revisit of the North Sumatra Basin (NSB) suggests that the basin remains attractive for exploration despite 90 discoveries made from 550 exploratory wells drilled since 1960. Over 8.6 BBOE in-place resource has been discovered, primarily gas and condensate. Almost 50% resources are stored in the Lower Miocene Peutu/Malacca Limestone reservoir. Exploration activity was halted between 1990 and 2000 due to a security situation, but it has been rebounded as marked by the discovery of Timpan-1 (2022). The NSB in general can be divided into two main terrains separated by the north-south Rayeu Hinge Line (RHL). The separation is supported by the underlying older rocks such as Tampur Formation to the east and metasediment rocks to the west. As a consequence, the Pase and Samalanga sub-basins sit above the metasediment rocks whereas the Tamiang and its adjoining offshore sub-basins are underlined by the Tampur Formation. The method used in this study is mainly through revisiting, compiling, and summarizing existing studies and reports such as from Pertamina Hulu Energi (PHE)-Elnusa Komitmen Kerja Pasti Jambi Merang (KKPJM) Study, Joint Studies, SKKMIGAS’ regional studies, S&P, Wood Mackenzie, published papers and other sources. The approach is by reviewing the underlying petroleum system in regard to the capability of each sub basin in generating hydrocarbon, modelling the migration fairway, and understanding the correlation between already discovered hydrocarbon and its potential source. Through statistical analysis the remaining undiscovered volumes generated by each sub-basin is estimated. Our analysis suggests that over 9 BBOE Yet-To-Find (YTF) in-place resources still remains in the NSB. Half of YTF sits in the Pase Low North and the other half is inside the Tamiang Low and its adjoining offshore half-grabens at Malacca shelf. Hydrocarbon generated in the Pase Low South is hypothesized to have been responsible to charge the giant Arun field and the fields at North Sumatra Offshore (NSO) area. With such understanding it is believed that Timpan-1 discovery which successfully tested hydrocarbon in the Oligocene Parapat play will be followed by other success of exploration prospects in this area. We encourage drilling deeper in the Tamiang Low to uncover the remaining potential as significantly thick sediment interval below the over-pressure zone in this area has not been penetrated. A more detailed mapping and stratigraphic correlation should be conducted to unlock the potential of the Oligocene carbonate/Tampur fractured dolomites in the Malacca shelf. Therefore, we recommend enriching the existing data set through multiclient surveys such as Full Tensor Gravity (FTG) over the onshore or transition area and 3D seismic over the offshore area. We also encourage the government of Indonesia to implement flexible and attractive fiscal terms to allow monetization of the resources as over 50 discoveries with a total of more than 500 MMBOE are currently stranded in this region.