Dorado Oil and Gas Development, Australia

Dorado oil and gas project is located in the Bedout Sub-Basin in Commonwealth waters, approximately 150km north of Port Hedland, Western Australia.

The project is owned by Joint Venture (JV) partners Santos (80%) and Carnarvon Petroleum (20%). Santos is the operator of the project.

The Final investment decision (FID) is expected in 2024, with operations commencing in 2025 and production in 2026.

Location details

Dorado oil field is located in the Roebuck Basin at a depth of 95m and about 110 km northwest offshore of Australia.

The integrated oil and gas project area extends across petroleum titles WA-437-P and WA-438-P. Production Licence for the project was granted in April 2022.

The JV partners received regulatory approval from National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) for the offshore project proposal (OPP) for the Dorado development in February 2023.

Dorado Appraisal Details

The Dorado-1 discovery was drilled in 2018 using Ensco 107 jackup drilling rig. The discovery comprises 162 million barrels of oil (MMbbl) and 748 billion Cubic Feet (BCF) of gas within multiple reservoirs of the Lower Triassic.

Dorado-2 and Dorado-3 wells were discovered in 2019.

Dorado-2 well was drilled using the jack-up mobile offshore drilling unit, Noble Tom Prosser in a water depth of 91m and reached a total depth of 4,57m. The well was drilled approximately 2km from the Dorado-1 discovery and encountered 85m of net reservoir in the primary Caley Formation. An oil-water contact was intersected at 4,003m measured depth, with 40m of net oil pay encountered.

The Dorado-3 appraisal well is located approximately 900m northwest of the Dorado-1. Noble Tom Prosser drilling rig was used to drill the Dorado-3 well.

Flow testing of the Dorado-3 appraisal well recorded a maximum flow rate of 48 thousand standard cubic feet (mscf)/day of gas and 4,500 barrels of crude oil (bbl)/day of oil from the Baxter reservoir, while the Caley reservoir achieved flow rates up to 11,100 bbl/day oil and 21mcf/day associated gas.

Dorado Development Reserves

Dorado is estimated to contain 162 million barrels of oil (MMbbl) (gross 2C) of Oil and Condensate, 748 billion Cubic Feet (BCF) of natural gas, and 344 million barrels of oil equivalents (MMboe).

The Dorado and Pavo fields together are estimated to contain gross 2C contingent resources of 189 million barrels of liquids and 401 petajoules of gas.

with approximately 1.5% of CO₂, the Dorado project is considered a very low CO₂ reservoir.

Infrastructure and Development

The Dorado project key infrastructure includes a 16-slot WHP with ten wells, an FPSO facility, subsea flowlines, and umbilicals between the WHP and the FPSO facility and potential future tiebacks.

Phase 1 development plan includes a WHP in 90m of water depth, connected to an FPSO vessel via sub-sea flowlines and control lines.

The FPSO will be located 2km from the WHP and will be connected to the seabed by a disconnectable turret mooring system.

The WHP will be an unmanned installation hosting the development wells and gas reinjection wells with processing facilities, remotely operated from the FPSO vessel. The FPSO will process the oil and gas being delivered from the reservoir via the wells and the WHP. The FPSO allows storage of oil and condensate and also offloading to a separate oil transport tanker.

Dorado project is planned to be designed for liquid handling rates of 100 thousand standard barrels per day (KSTB/d) and a gas reinjection capacity of 235 million standard cubic feet per day (MMscf/d) over a period of 20 years.

Dorado oil and gas project is planned to be developed in two phases. Phase 1 development involves the production of oil and condensate through a wellhead platform (WHP) and Floating Production Storage and Offloading system (FPSO). Gas is planned to be reinjected in phase 1 to enhance oil and condensate recovery.

Phase 2 development involves recovering and piping the gas to the Western Australian domestic and LNG markets. The initial gross oil production rate from the field is targeted at 100,000 barrels per day.

Pavo North oil discovery

the JV partners commenced the Pavo-1 exploration well, located 46 km east of Dorado in a water depth of approximately 88m In February 2022.

The JV partners are planning to assess the required changes to the Dorado FPSO vessel to incorporate an additional 43 million barrels of resource (gross, 2C) from the Pavo discovery into the FPSO, and process and store along with the Dorado production.

Contractors Involved

MMA Offshore was awarded a contract by Santos to support its Dorado jack-up drilling campaign in 2019. The scope of work includes rig tows to and from the field, infield rig moves, and platform supply duties in support of the Noble Tom Prosser rig.

In August 2021, Santos awarded a FEED contract for the Dorado project FPSO facility to Altera Infrastructure. Santos awarded a FEED contract for the design, construction, and installation of the WHP to Sapura Energy.