The Frigate-1 wellhead is located within the Petroleum Retention Lease WA-40-R. It is at a water depth of approximately 112m, is 101 km from the closest shoreline and 186 km from the nearest landmark, Kalumburu.

The Frigate-1 exploration well was drilled in 1978 by ARCO Australia Ltd. No hydrocarbons were encountered, and the well was plugged and abandoned in the same year.

Santos became the titleholder of WA-40-R in 2011 and is now proposing to permanently abandon the wellhead in-situ. An options assessment conducted by Santos determined that in-situ abandonment is the preferred decommissioning option based on environmental criteria.

A wellhead survey will be undertaken as part of this Environment Plan to validate the assumptions made within the options assessment. The survey may take up to 7 days, including time to locate the well. The ROV inspection of the wellhead itself is expected to take approximately 4 hours. This survey is notionally proposed to take place in September 2022.

In the event that the survey reveals an unforeseen outcome not evaluated in the options assessment, the Santos Management of Change process described in EP will be followed and Regulations 7, 8 and 17 of the OPGGS(E)R 2009 considered.