Western Gas is proposing to permanently leave in situ a total of four subsea wellheads associated with four abandoned exploration wells, namely Chester-2, Glencoe-2, Mentorc-2 and Snapshot-1 in Petroleum Permits WA-70-R and WA-474-P. Plugging and abandonment of these wells has already occurred and are described in the accepted Well Operations Management Plan (WOMP) and Well Abandonment Reports for each well.

In addition, the Glenloth-1 well is to temporarily remain as a suspended well. Western Gas is proposing to undertake annual vessel-based wellhead survey activities on the suspended well, which is located in Petroleum Permit WA-70-R.

All wells are located approximately 180 km northwest of Onslow and 150 km north of Exmouth, Western Australia at water depths between 1,116 and 1,131 metres.