ANALISIS STRUKTUR GEOLOGI DAN REKONSTRUKSI PALINSPASTIK PADA SUB-CEKUNGAN TARAKAN

Abstract

The aim of this research is to create and aplicate palinspastic reconstruction on the onshore part of the Tarakan sub-basin and to link it to the existing petroleum system in the basin. The tarakan sub-basin is bounded by the Tidung sub-basin in the north, Muara and Berau sub-basins in the south, Sekak High in the west, and Makassar Strait in the east. The quality of the seismik data is fair to poor due to the influence of coal deposits on the onshore part and it adds the difficulty of the seismik interpretation process in this area.

After analyzing the seismic data and well data, palinspastic reconstruction is performed to reconstruct and model the depositional conditions of each rock formation during deformation at each geological age. Based on the results of the analysis, it is known that at the age of Pliocene before the regime changes, the total strain was 0.8%. The strain value is positive and in accordance with the working regime, that is, the extensional regime with the results of the crosssection lengthening. After the inversion process, the strain value was -1.83%. This negative value proves that there is indeed a compression process caused by the inversion so that the cross section is shortened. The result of the strain calculation above is in accordance with the existing regional geoloy, where extension regime happened at the age of eocen to Pliocene and at the age of Pliocene there was an inversion that caused the regime changes to a compression regime.

If we connect it with the existing petroleum system, the results add to the possibility of hydrocarbon traps that are formed structurally or anticlinal traps in addition to the already proven play in deltaic stratigraphic trap at the age of Miocene.