The Tomori Basin is on the eastern arm of Sulawesi, spanning the Provinces of South Sulawesi and Central Sulawesi Province, to the offshore of Tolo Bay. Part of the Tomori Basin in South Sulawesi Province includes one regency area, namely East Luwuk Regency with Malili as the capital. The Tomori Basin in Central Sulawesi Province includes two regency areas, namely Morowali Regency with Bungku as its capital and North Morowali Regency with Kolonedale as its capital.

Surface geology research has been carried out in the Tomori Basin around Upper Kolo to Kolonedale. 2D seismic has also been carried out by Pusdatin and PND, gravity and magnetotelluric surveys by the Geophysics Team of the Center of Geological Survey. Apart from that, there are already drilling wells in this basin. The Tomori Basin research produced several data, the main of which were measurements and sampling of the Tokala Formation, Nanaka Formation, Tetambahu Formation, Matano Formation, Salodik Formation and Tomata Formation. The Tokala Formation is composed of alternating sandstones and shales with chert lenses, mostly deformed by faults, folds and joints. This formation was formed in a shallow to deep marine environment from the Triassic to Jurassic ages. In the Upper Kolo area, oil seeps were found coming out of this formation. The Nanaka Formation is formed overlapping the Tokala Formation. This formation is composed of layers of sandstone and alternating sandstone with shale at the bottom. Some exposed rocks have also been deformed due to faults, joints and folds. This formation was formed in the Middle to Late Jurassic (Simandjuntak, 1994). The Tetambahu Formation is formed overlapping the unconfirmity above the Nanaka Formation. This formation was formed in the Late Jurassic (Simandjuntak, 1994). This formation is composed of limestone with chert inserts, layer thickness between 12-20 cm. Well exposed and deformed by faults, joints and folds. The Matano Formation forms overlapping above the Tetambahu Formation. This formation is composed of limestone with lenses or chert nodules. Well exposed and deformed faults, joints and folds. This formation was formed in the Late Cretaceous (Simandjuntak, 1994). The Salodik Formation forms unconfirmity overlapping the Matano Formation. This formation is well exposed, composed of relatively deformed limestone with joints. The Salodik Formation was formed during the Eocene to Middle Miocene in a shallow marine environment (Simandjuntak, 1994). The last formation that can be found in the study area is the Tomata Formation. This formation was formed in the Late Miocene to Pliocene. Composed of alternating shale, sandstone, conglomerate and lignite inserts. From several samples, geochemical, maceral and GC-MS analyses were also carried out, so that the results obtained were that the samples from the Tetambahu Formation dominated and were gas prone, maturity level was immature. Gravity and magnetotelluric analyzes in the Tomori Basin have been carried out and interpreted by forming cross-sectional lines. From the existing values, it can be seen that the structures that develop in this basin are relatively diverse and still expanding.

The Tomori Basin is one of the proven productive basins. The wells in this basin include Tiaka-1, Tiaka-2, Tiaka-3, Tolo-1, Matindok-1, and others. Of the many wells, only some of which have been considered proven to have found oil, namely the Tiaka-1, Tiaka-2 and Tiaka-3 wells, besides that what was found was gas and/or condensate. Currently, the Tiaka-1 and Tiaka-2 wells are still producing.From the seismic results and interpretation of well data, it can be seen that most of the target layers are upper Miocene carbonate rock layers, the depth of each well varies but is between 2000-4000 meters. Based on the results of field research, formations that have the potential to be carriers of hydrocarbon source rock are shales from the Tokala Formation and the lower part of the Nanaka Formation. The potential reservoir rocks are the upper sandstones of the Nanaka Formation, the limestone of the Salodik Formation with fractured reservoirs. Meanwhile, the sandstone-silt layer of the Tomata Formation has the potential to be used as cap rock in the study area. From the results of research and interpretation, it can be seen that the concept of each well and the findings are different and very dependent on the developing petroleum system. Based on observations and interpretations of surface and subsurface data, in general there are two petroleum systems that have developed in this basin, namely the Cenozoic system and the Mesozoic system. Until now, it has been proven that the target is from the Cenozoic system or the Salodik group layer (Tomori, Minahaki and Matindok).