A joint venture of Santos Ltd. and Carnarvon Petroleum Ltd. reported the Roc South-1 well, drilled between the previous Roc and Dorado discoveries in permit WA-439-P in the Bedout subbasin offshore Western Australia, has been plugged as a dry hole.
Despite intersecting the Crespin and Milne reservoirs like those at the Dorado discovery, logging tools found no evidence of producible hydrocarbons. The well was drilled to a total depth of 4,910 m but not as deep as originally planned due to the lack of hydrocarbon indicators.
Adrian Cook, Carnarvon managing director, said Roc South-1 was the first of the eight wells drilling in the basin not to discover producible hydrocarbons and the combine will now analyze the result to determine a reason. Cook put a positive spin on the well when he added that the quality of the reservoir sands found in the well were excellent.
Cook said the results will be incorporated with those of the new Keraudren 3D seismic survey to refine understanding of the region for future exploration drilling.
Roc South-1 was drilled to determine if additional hydrocarbons existed that could be tied in and produced with the planned Dorado development facilities. Cook said plans for Dorado won’t be impacted by the Roc South-1 results.
Independent appraisal
Regarding Dorado, Carnarvon engaged international firm ERC Equipoise Pty. Ltd. to conduct an independent review of the Dorado resource following the success of Dorado-2 appraisal earlier this year.
Equipoise calculated a 1C unrisked contingent resource oil and gas combined figure for the field of 176 million boe, substantially higher than Carnarvon’s unrisked estimate in August last year of 128 million boe.
Equipoise put unrisked oil and condensate at 86 million bbl for unrisked 1C resource and 162 million bbl of unrisked 2C resource.
Cook said the new figures provide the JV with a high degree of confidence to advance field development concept evaluation work and confirm that the group has discovered a very large field.
The volume of gas—unrisked 2C resource of 748 bcf calculated by Carnarvon last year, but unaudited by Equipoise—is also a large resource, particularly when combined with the nearby Roc field resource of 332 bcf of 2C gas and 20 million bbl of condensate.
Upon completion of Roc South-1, the rig will be moved to drill Dorado-3.
Santos has 80% of the discoveries. Carnarvon has 20%.
