Triassic Petroleum System as an Alternative Exploration Concept in Offshore Western Timor, Indonesia
Penulis/Author
Prof. Dr. Ir. Sugeng Sapto Surjono, S.T., M.T., IPU., ASEAN.Eng. (1); Rahmadi Hidayat, S.T., M.Eng., Ph.D. (2); Naryanto Wagimin (3)
Tanggal/Date
19 2017
Kata Kunci/Keyword
Abstrak/Abstract
Offshore Western Timor has different exploration concept from the proven Abadi Gas Field that is
located at northwestern part of Bonaparte Basin. Classic Jurassic petroleum play, as a proven
reservoir and source rock, did not develop in study area due to severe erosion during the Valanginian
time. Therefore, the Triassic interval has to be assessed to reveal an alternative petroleum system in
Offshore Western Timor. Petroleum System Analysis utilising 2D seismic and data from three
exploration wells has been performed to construct petroleum exploration concept. The study showed
that the Scythian Mount Goodwin interval could be considered as a primary gas-prone source rock,
with kerogen type II/III; total organic content up to 2.09%; and hydrogen index which could reach
569 mg/g. Based on pseudo-well conducted in this study, Mount Goodwin interval has reached gas
generation in the Early Cretaceous and expulsion in the Eocene times. Reservoirs are provided by
Carnian-Ladinian Challis and Anisian Pollard intervals. The Challis interval as the main reservoir is
typical shoreline sandstone, interbedded with claystone and limestone intercalations. Petrophysical
and petrography studies in this interval indicate good reservoir properties. On the other hand, the
Pollard interval has poorer properties, which mainly consists of platform mudstone with minor
claystone. Intra-formational shale of Challis is considered as the potential regional seal, for the area
that is not truncated by Valanginian Event. In the optimistic exploration point of view, the Jurassic
northeast-southwest tilted fault blocks are still favourable for exploration drilling in the Offshore
Western Timor area.
