Santos Ltd., Adelaide, and its joint venture partner Carnarvon Petroleum Ltd. have started a 3D seismic survey over the Dorado, Roc, Roc South, and near-field prospects in the Bedout subbasin offshore north-western Western Australia.
The survey is taking place at the same time as the group is drilling the Dorado-2 appraisal well in permit WA-437-P.
Three prior 3D surveys have been carried out in the contiguous permits (WA-435-P, WA-436-P, WA-437-P, and WA-438-P) designed with an exploration focus that enabled the companies to make the Dorado and Roc discoveries in WA-437-P as well as identify many other prospects and leads.
The new Keraudren 3D is designed to assist with the advancement of the Dorado oil and gas field development and to prepare for the potential drilling of some high-graded exploration targets, such as Pavo and Apus.
Particularly it is hoped that the new survey will improve the data quality over the Caley, Crespin, Baxter, and Milne reservoirs, which contain substantial quantities of oil and gas in the Dorado-1 discovery well.
The survey covers just in excess of 3,000 sq km and will take about 70 days to acquire. Processing of the data will be fast-tracked to be available for interpretation early in 2020. This will enable the information to be incorporated into Dorado field development planning to support a final investment decision scheduled for late 2020.
Meanwhile, Dorado-2 appraisal has already encountered a similar reservoir to those in Dorado-1. Some 233 m of whole wellbore core has been cut through the Caley and Baxter reservoirs and the well is nearing its planned TMD of 4,548 m.
Operator Santos will then run wireline logs over the complete section of open hole encompassing all four reservoir members. The log program will include fluid sampling and pressure testing to determine the reservoir quality, the nature of the hydrocarbons present, and estimates of oil-water contacts.
Dorado discovery was made in July-August 2018. Dorado-2 is about 2.2 km and downdip from the discovery, which is 160 km north-northeast of Port Hedland on the Western Australian coast. The well is being drilled by the Noble Tom Prosser jack up rig in about 95 m of water.
Dorado-2 is the first of a three-well program for this year and will be followed by Roc South-1 about 13 km from the crest of the Dorado structure, and then Dorado-3.
Santos has an 80% interest with Carnarvon holding 20%.
