Toward less carbon-intensive, faster gas-to-market offshore development schemes a case study of using discovered resources in the Bedout Sub-basin

Abstract

The Dorado and Pavo fields in the Bedout Sub-basin of the Roebuck Basin, offshore Western Australia, boast a combined 2C contingent resource of 210 MMbbls of liquid hydrocarbons and 750 bcf of gas. Their discovery represents a significant development opportunity for the Australian offshore, especially given the considerable un-risked Prospective Resources in the basin. However, Dorado faces challenges due to its high volatile oil/high condensate gas ratio gas (wet gas) accumulation and its reservoir pressure exceeding 5500 psia, necessitating a miscible gas injection strategy to maximise liquid recovery. This approach involves energy-intensive gas processing and high-pressure reinjection, leading to substantial greenhouse gas emissions. The CO2 intensity directly from Dorado compressors is estimated at 30–39 kg/bbl – on a project-level nearly double the average unit emissions of many producers. This paper explores alternative development schemes using public domain information and petroleum engineering principles to mitigate technical risks, reduce CO2 emissions, and possibly improve the economics and development timeline of the Dorado and Pavo fields. For Dorado, a simpler scheme focussing on oil production and gas delivery for domestic or liquefied natural gas (LNG) use could significantly reduce emissions. Meanwhile, Pavo might see development via a standalone FPSO, emphasising reservoir energy management through water flooding and produced water disposal, typical of conventional black oil field development. These alternatives aim for a less carbon intensive and economically viable development pathway, setting a precedent for future exploration and development in the basin.