A SEMI-REGIONAL PLAY ANALYSIS OF THE OMBILIN BASIN TO UNDERSTAND THE TECTONO-STRATIGRAPHIC FRAMEWORK AND IDENTIFICATION OF POTENTIAL EXPLORATION OPPORTUNITIES

摘要

The Ombilin Basin is located next to Indonesia's most prolific oil-producing basin: The Central Sumatra Basin (CSB), i.e. Minas Field, 8 BBOE (Greaser et al., 1996). An earlier study by PT Rizky Bukit Barisan revealed that this basin potentially holds up to 60 MMBOE of oil and condensate. Based on the physiography of Sumatra Island, the Ombilin Basin was classified as a Tertiary intermontane basin (Koesoemadinata and Matasak, 1981). The basin is situated within the continental crust along the Sumatra Fault Zone (SFZ). surrounded by a more recent magmatic arc. The magmatic arc, however, did not necessarily affect the basin's geothermal gradient (Koning, 1985). These complexities make the basin modelling process even more problematic, considering the already complex tectono-stratigraphy and leaking faults. Therefore, a deep understanding of structurally related sedimentary processes and in-depth fault seal analysis are important. The objective of this study is to analyze on more play concepts that have not been the focus of the previous exploration to expand the knowledge to unlock exploration possibilities within the basin. Using the new drilled wells combined with the surface oil seep and newly processed seismic, a new perspective in hope to find more resources within this basin can be reinforced using the integration of Basin Modelling and Advanced Seismic Processing, 5 prospects within 2 reservoir intervals were identified. Monte Carlo simulation was also applied to understand the impact of uncertainty-related information to help de-risk all of the potential prospect so that all of available resources can be used effectively. Altogether, a potential oil of 98.85 mmbls and condensate of 62.76 MMSCF was accumulated and documented within this study. Furthermore, the study documents new methods of exploration in Intramontane basin, this will enable readers to learn and as a guide for designing a future exploration and development in an Intramontane basin, not only but especially in Indonesia.