Hydrocarbon exploration in the eastern part of Timor island was carried out since 1908 based on evaluation of the geological surface and hydrocarbon seepages data only. In 1914-1916 the Portuguese colonial government drilled several shallow wells with various total depth between 10-175 m. One well was reported as an oil blow out. Until early of 1970’s more than 21 wells drilled in this area. The significant petroleum were found in the Matai # 1 (180 BOPD) and Cota Taci # 2 (200 BOPD) drilling wells.
The tectonostratigraphy of the studied area, broadly divided by two different megasequences. The first one is referred to the Pre-Collision times which dominated by Pre-Tertiary sediments. The other one is commonly referred to the Post-Collision times which consist of Late Miocene-Recent ages of sediments. This Post-Collision sediments was deposited in Suspended Basin. This study indicates two prominent hydrocarbon play types in the area : (1) Pre-Collision Play Type which is mainly thrusted anticlines. The reservoirs are sandstone layers of the Atahoc, Cribas, Aitutu and Wailuli Formations and also the fractured Borolalo and Bobonaro limestones Formations; (2) Post-Collision Play Type mostly rollover anticlines on the downthrown blocks of listric faults. The reservoir are Late Miocene Viqueque sandstones. The Atahoc, Cribas and Wailuli shales have been considered as potential source rocks for both plays.
Authors : Khozin Sahudi & Ridwan Nyak Baik