Dorado discovery – unlocking a major new oil and gas play in the Bedout Sub-basin

Abstract

In 2014, Santos (formerly Apache and Quadrant Energy Limited) acquired an operated exploration position over most of the under-explored Bedout Sub-basin. A multi-year exploration program was subsequently executed, targeting plays within Middle Triassic fluvio-deltaic sediments of the Lower Keraudren and Archer formations. Initial wells at Phoenix South and Roc established the presence of high-quality reservoirs, source rocks and hydrocarbon fluids, but the commerciality of these discoveries was impeded by the lack of existing production infrastructure in this frontier basin. In 2018, Santos and its Joint Venture partner, Carnarvon Petroleum, drilled Dorado-1, targeting stacked Archer Formation reservoirs in an erosional truncation trap set up by a major canyon system. The well encountered light oil and/or condensate rich gas in high-quality reservoir sands at each of the target intervals. Despite limited well control, burial depths on the order of 4000 m and imperfect seismic data, the pre-drill prognosis was remarkably accurate, largely due to the application of modern seismic inversion techniques. Subsequent appraisal drilling undertaken during 2019 demonstrated the discovery is larger than originally anticipated and has significantly de-risked a future development. New seismic acquired during 2019 will be used to further improve the understanding of Dorado reservoirs and to mature follow-up prospects for future drilling.