Australia: Roc South well fails to deliver for Santos

Following last week’s results from the first two targets, which proved to be dry, Australian energy giant Santos has failed to find hydrocarbons at the other two Roc South-1 targets as well. The rig will move on to the next well location soon. 

Noble Tom Prosser rig
Noble Tom Prosser rig
Noble Tom Prosser rig

Roc South-1 is located in WA-437-P where Santos is the operator and Carnarvon Petroleum is its partner. It is an exploration well with primary objectives in the Caley, Baxter, Crespin and Milne Members of the Lower Keraudren Formation.

Santos spudded the Roc South-1 well in mid-June, using the Noble Tom Prosser jack-up rig, with hopes to discover and add tie-in resources to the nearby Dorado oil field, one of the largest ever oil discoveries in Australia’s North Western Shelf.

Last week, Carnarvon said that no producible hydrocarbons had been found across the Caley and Baxter sands.

On Monday, July 15 Carnarvon provided an update related to the Roc South-1 well. The company said that the 7” liner was set in place as planned and the well was drilled down to total depth of approximately 4,910 meters Measured Depth (MD) in 6” hole.

The well was not drilled as deep as earlier planned due to lack of hydrocarbon indicators. The interpretation from logs indicates no producible hydrocarbons across the Crespin and Milne sands.

According to Carnarvon, the rig will complete operations to secure the well before moving to the Dorado-3 well appraisal location.

The Caley, Baxter, Crespin and Milne reservoir sands were of similar quality reservoir in the Roc South-1 well as compared to the nearby Dorado field.

Carnarvon Managing Director, Adrian Cook, said: “Of the eight wells that we have drilled in this new basin, this is the first well to not discover producible hydrocarbons. We will need to analyse the reason for this result, however a strong positive take away is the quality of the reservoir sands found at depths of almost 5,000 meters. As we continue to build our understanding of the area, we will incorporate all of our well results, together with the new Keraudren 3D seismic survey, to refine our prospectivity for future exploration drilling. We remain firmly of the view that we are working in a highly promising new basin with very high-quality prospects to be pursed in the future.

“The rig will soon move to the Dorado-3 appraisal well location where it is planned to extract several cores and conduct flow tests from the Dorado reservoirs that have proved successful in both the Dorado-1 and 2 wells. Given our understanding of the Dorado-1 and 2 reservoirs, and the successful flow test at Roc-2, we are looking forward to the Dorado-3 results providing us with strong support for our development plans.”

The objective of the Roc South well was to determine if additional hydrocarbons existed that were capable of being tied-in and produced with the Dorado liquids (oil and condensate) and gas production facilities. Carnarvon said that the development plans for Dorado will not be impacted by the Roc South results.

In relation to the other exploration prospects in the area, the final Roc South-1 result is expected to assist in their refinement. However, the new 3D seismic data that has essentially completed acquisition over the core area, is expected to provide more relevant information over both the Dorado development area and a number of key prospects nearby, Carnarvon concluded.

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