Publications

Tectonically, the Salawati Basin is defined as a Cenozoic foreland basin with wedge top area on the northern part bounded by Sorong fault zone, fore-deep area elongated from east to west area, fore-bulge area uplifted in the eastern part. Hydrocarbon exploration in the Salawati Basin have been started since the 1930s and more than 800 exploratory and development wells have been drilled. A total of around 750 MMBOE have been discovered using a single proven petroleum system, which is Miocene build up carbonate of Kais Fm, sealed by Miocene-Pliocene shale facies of Klasafet Fm and Lower Klasaman Fm. and charged from Miocene shale of Klasafet Fm during Early Pliocene related to Sorong fault activation. Based on Salawati Basin creaming curve, the discovery of Kasim, Walio, Jaya, TBA, TBC, Arar, Klalin and Matoa structures during the 1970s to 1990s were marked as the 1st cream with the largest oil discovery of up to 215 MMBOE being the Walio structure in 1973. The largest gas discovery of up to 331 BCFG is the Klalin structure in 1986. Unfortunately, due to uneconomic and unsuccessful well drilling during the past 10 years, the exploration trend has become flat. The worst-case scenario is that exploration activity will slowly bring to and end if we still rely on the proven Miocene petroleum system. The latest age biomarker analysis of DST-1 oil sample, tested in Early Miocene limestone of Faumai Fm, in the Kawista-1 well shows low oleanane index which indicates possible Mesozoic oil origin. This result has triggered several activities such as geological field mapping and 3D seismic survey to further evaluate the Paleozoic-Mesozoic petroleum system in the Salawati basin. The preliminary evaluations of new 3D seismic data shows there are seismic reflector packages beneath Base of Paleocene-Eocene Faumai Fm., which are thickening to the north-eastern and eastern part of the Klamono Area. Although no wells have ever penetrated these reflectors packages, we interpreted it as possible Mesozoic sediments. This interpretation is supported by geological mapping data in the Sorong Fault Zone, which is located in the Makbon area. The Jurassic-Triassic shale and sandstone outcrop are still clearly observed. We believed that Sorong Fault cut through Mesozoic graben and popped-up Mesozoic sediments along the Sorong Fault Zone. These findings have opened the possibility of Paleozoic-Mesozoic hydrocarbon potential in the Salawati Basin, especially in the Klamono area. However, further evaluation still needs to be carried out, such as Basin Modelling, to have better understanding of the Mesozoic petroleum system in this area.