The Woollybutt Field is located approximately 80 km off the northwest coast of Western Australia in Lease Area WA‐25‐L. The Field is approximately 25 km west of the Barrow Island Marine Management Area and Marine Park boundary, and more than 50 km south‐west of the proposed Montebello Commonwealth Island Marine reserve.
The Woollybutt Field is presently shut‐in and will continue to be shut‐in during field management activities. A summary of the proposed field management activities is outlined below.
1. Field Management Activities
Field management activities that may be undertaken in accordance with this EP include cathodic protection surveys and visual inspections, these are undertaken using remotely operated vehicles (ROV). The methods used by Eni are well understood and do not represent any novel techniques or equipment. Details of the frequencies and durations of field management activities are provided in Table 1.
Table 1: Proposed field management activities with indicative frequencies and durations
Activity
Frequency
Approx. Duration (days)
ROV Survey
Opportunistic – no more than once per year
3 – 7 days
1.1 ROV Surveys
Cathodic protection surveys and visual inspections of subsea structures will be undertaken using ROVs, deployed from a project vessel. Cathodic protection surveys are undertaken as part of an asset integrity. Cathodic protection readings have remained consistent over the last three surveys conducted in 2010, 2014 and 2016.
1.2 Project Vessels
Project vessels will be selected based on the activity that will be undertaken. All project vessels will be commercial vessels with a suitable survey class for activities in the Operational Area. The maximum credible spill scenario for all project vessels is 100 m³ (volume of largest tank). All project vessels will run on marine diesel; no intermediate or heavy fuel oils will be used. Typical vessel specifications are detailed in Table 2.
Table 2: Typical vessel specifications
Parameter
Description
Draft (max)
3.25 (max)
Gross tonnage
1475 Gt
Hull
Steel hull
Fuel type
Marine diesel
Total fuel volume
138.2 m3 (100%)
Volume of largest fuel tank
30.4 m3
