West Australian Petroleum (WAPET) discovered the first of the Greater Gorgon gas fields, West Tryal Rocks, northwest of Barrow Island in 1973. The West Tryal Rocks field is located approximately 55km northwest of Barrow Island and approximately 145km north of Onslow.

The West Tryal Rocks 2 (WTR-2) well was drilled and abandoned by WAPET within exploration permit WA-25-P in 1974. Following abandonment, the wellhead was left in situ. In 1991, the relevant graticular blocks were excised from WA-25-P and became the current retention lease WA-5-R.

In 2000, Chevron Australia Pty Ltd (CAPL) became the operator of the oil and gas exploration and production assets previously managed by WAPET, including retention lease WA-5-R.

This Environment Plan covers the impacts and risks associated with the WTR-2 wellhead remaining in situ.