Publications

According to published models, Miocene coaly source rocks in the Mahakam Delta occur in shelfal areas, but are thermally postmature on the Makassar Slope. However, our reinterpreted seismic and sequence stratigraphic data show that much of the source rock on the slope is in the oil and gas window. Our new model identifies highstand and lowstand kitchens and upgrades the oil potential of the outer shelf, where it influenced drilling that resulted in major oil discoveries. The new model predicts distinct oil accumulations charged from local kitchens between anticlinal structural trends aligned parallel to the present-day coastline. High-resolution geochemistry confirms that oils from these trends differ genetically. Waxy highstand oils occur onshore and originated near peak oil window from Middle-Upper Miocene coals and shales deposited in coastal plain highstand kitchens. Less waxy lowstand-1 oils occur offshore and originated in the early oil window from Middle-Upper Miocene coaly source rocks deposited in deepwater lowstand kitchens. Most lowstand-2 oils show higher maturity than lowstand-1 oils and originated from Lower- Middle Miocene coaly source rocks. Low-maturity, nonwaxy transgressive oils occur onshore and originated from Middle Miocene marine shales deposited near maximum flooding surfaces. Advanced 3D fluid-flow models using measured source-rock kinetics correctly predicted oil and gas rather than gas at the recent deepwater Merah Besar and West Seno discoveries.