Publications

Early drilling results from a new exploration play in the northern and southern Makassar Straits have proven the critical hydrocarbon system elements for an Oligocene to Eocene carbonate play in the complex structural terrain of offshore, west Sulawesi. ExxonMobil has drilled the first four wildcats testing the play in different structural positions and highlighting important exploration learnings that have broader application for evaluating remaining undrilled prospects in the play and similar deepwater provinces elsewhere in Indonesia.Previously published evaluations of the petroleum potential of the deepwater Makassar Straits are characterized by conflicting geologic models and play types. Basin fundamentals, including crustal type and grain, have not been agreed upon resulting in significant uncertainty concerning the presence or absence of associated play types (e.g., Tertiary carbonates deposited on extended continental crust or play extension of Mahakam deep water clastic reservoirs). ExxonMobil has approached exploration of the basin with an integrated processbased approach supplemented by decades of experience in Indonesia and a global perspective.Exploration acreage was offered by the government and picked up by industry in 2006 and 2007 when ExxonMobil was awarded the Mandar and Surumana Production Sharing Contracts (PSCs).New data acquisition programs, including 2D and 3D seismic, marine gravity and magnetic, and seafloor drop core surveys, were acquired and incorporated into the play evaluations. Drilling results from the early wells have helped clarify exploration models and penetrated carbonate reservoirs within the play demonstrating hydrocarbon charge, moderate to good reservoir quality and variable seal potential.This integrated basin approach has greatly reduced uncertainty and identified fairways of continental extension with high-graded potential for carbonate reservoirs on structural highs and mature syn-rift source rocks in adjacent grabens. While early results are encouraging, the efficacy of the overall hydrocarbon system will be tested by industry drilling over the next few years.