East Coast Supply Project - Annie-2 Development Well Environment Plan

To help meet east coast domestic demand, subsea gas reserves need to be developed to replace existing wells as they run out. Imported alternatives cost significantly more and cause much higher emissions. The East Coast Supply Project (ECSP) - Annie-2 development well Environment Plan provides for the drilling of a single development well named Annie-2. Annie-2 will be tied into our existing subsea pipeline to allow hydrocarbons to be transported to our Athena Gas plant. 

Update log

• March 2025: Page created

Location

Adjacent to Athena gas plant, Otway Basin, 9km offshore Peterborough and Port Campbell, Victoria in Commonwealth waters. 

Offshore Eastern Maar Sea Country.

Activity details​

We plan to: 

• Drill the Annie-2 development well
• Well clean up and flowback
• "Complete" the well for production
• Suspend/shut in the well for future connection to our existing pipeline
• Survey the seabed with a support vessel
• Carry out inspection, maintenance and repair with with a support vessel using tools that include:
  • remotely operated vehicles (ROV)
  • side scan sonar
  • multi-beam echosounder
  • magnetometer.

Distance from shore

Approximately 9 km

Permit area

Vic P44

Water depth

Approximately 55 m

Supply base

Portland

Summary of Impacts, Risks and Activities

Information Sheet  regarding impacts, risks and control measures.

Timeline

7 days per survey, ~60 days for well construction. Activities are planned to be carried out sometime during the period 2026 to 2028 inclusive.

Identified impacts and risks

Interaction with other marine users

• Mobile Offshore Drilling Unit (MODU or drill rig) and support vessel operations: Presence will be temporary with vessels mobilised from Portland or Geelong/Melbourne area
• Permanent presence of one well likely encompassed by a 500m PSZ. The final well locations may vary by up to 500m to accommodate seabed features and engineering constraints identified at the survey stage.

Impacts

• Changes to the functions, interests and activities of other marine users

Controls

• Temporary Exclusion Zones will be communicated via Notice to Mariners
• Fisheries damages protocol
• Ongoing consultation and notification
• Marine assurance process

Seabed disturbance

Our proposed activities offshore include:

• putting down anchors and grounded chains temporarily to position our mobile offshore drilling unit
• pre-laying anchors using our support vessel
• 'flying' our ROV (remotely operated vehicle) close to seabed
• depositing cuttings such as rock and natural material generated during drilling of the wells
• depositing excess cement on seabed

Impact

• Change in benthic habitat

Risks

• Marine fauna injury or mortality
• Cultural heritage changes.

Controls

To mitigate or reduce these impacts and risks we will implement the following controls:

• Planned maintenance system
• Offshore work procedures
• Marine assurance process
• Underwater cultural heritage disturbance risk management process

Underwater sound

Underwater sound will be generated from the following activities:

• MODU operation: Continuous sound through general operations and utilisation of  thrusters when and as required for moving and holding position. Indicative MODU is shown below  1.
• Support vessel operation: Continuous sound through propeller and thrusters when moving and holding position. Indicative support vessel is shown below.
• ROV operations
• Drilling operations: Equipment vibrations and the rotating drill string will produce noise at each well location.

Impact

• Change in ambient sound

Risks

• Behavioural change in marine fauna (marine mammals, marine turtles, fish)
• Auditory impairment (marine fauna)

Controls

• Victoria Whale Disturbance Risk Management Procedure to ensure our activities are not inconsistent with relevant EPBC species recovery plans
• Marine Assurance Process
• Offshore Operational Procedures

Greenhouse gas emissions

Greenhouse Gas (GHG) emissions are generated by the following activities:

• Well clean-up and flowback: Direct emissions are generated when the well is flowed to remove contaminants with gas sometimes returned to the MODU. This gas is flared for safety purposes which is estimated to take approximately 1 day.
• MODU and support vessel operations: The MODU and support vessel generate direct emissions by their use of diesel or gas to generate power for operation. Indirect emissions are generated through the purchase of products such as cement and the waste generated.

Impacts

• Increase in greenhouse gas emissions
• Change in climate systems
• Change in ecosystems
• Change in Socio-economic factors

Controls

• Marine assurance process
• Cooper energy emissions reduction protocol

Light emissions

Our proposed activities offshore that may result in light emissions include:

• Vessel operations

Impact

• Change in ambient light

Risks

• Change in fauna behaviour

Controls

To mitigate or reduce the impacts and risks of our activities we will:

• Conduct a pre-campaign risk review for light
• Implement Marine Assurance Process (e.g. comply with Marine Order 30)
• Implement Light Management Measures (e.g. Vessel non-essential light positioning)

Other atmospheric emissions

Our proposed activities offshore that may result in Atmospheric Emissions include:

• Vessel and MODU operations
• Helicopter operations

Impact

• change in air quality

Controls

To mitigate or reduce the impacts and risks of our activities we will:

• Implement a Marine Assurance Process for vessels

Planned discharges

Our proposed activities offshore that may result in planned discharges include:

• Vessel operations
• Installation of subsea structures
• Maintenance and repair

Impact

• change in water quality and change in sediment quality.

Risks

• injury / mortality to marine fauna.

Controls

To mitigate or reduce the impacts and risks of our activities we will:

• Implement a Marine Assurance Process
• Implement an Offshore Chemical Assessment Procedure
• Ensure the vessels meet emissions and discharge standards  prior to commencing an offshore activity
• Undertake a campaign risk review

Invasive marine species

Activities

• Ballast water adjustments by MODU and / or support vessels to maintain stability.
• Biofouling by MODU and / or support vessel through IMS presence on submerged surfaces

​​Risks

• IMS transferred into field, establishes and spreads.
• IMS is transferred between vessels, establishes and spreads to other areas.
• IMS is transferred out of the field and establishes outside the region and spreads.

Controls

• IMS Risk Management Protocol
• Australian Biofouling Management Requirements

Unplanned interactions with marine fauna

Our proposed activities offshore that may result in unplanned interactions with marine fauna include:

• Vessel and MODU operations

Risks

• Injury / mortality to marine fauna.

Controls

To mitigate or reduce the impacts and risks of our activities we will:

• Implement Offshore Operational Procedures (e.g. distances and management practices for interacting with cetaceans)
• Implement Offshore Victoria Whale Disturbance Risk Management Procedure to ensure our activities are not inconsistent with relevant EPBC species recovery plans

Accidental or uncontrolled hydrocarbon release

Our proposed activities offshore that may result in accidental hydrocarbon release include:

• Vessel operations
• MODU (drilling) operations

Impact

• Change in water quality

Risks

• Change in habitat
• Change in fauna behaviour
• Injury / Mortality to Fauna
• Changes to the Functions, Interests, or Activities of Other Users

Controls

To mitigate or reduce the impacts and risks of our activities we will:

• Implement a Marine Assurance Process (e.g. compliance with Marine Orders)
• Implement Marine Exclusion and Caution Zones
• Undertake ongoing engagement
• Maintain an Operational and Scientific Monitoring Program
• Have an accepted Oil Pollution Emergency Plan for the activity
• Have regulatory Safety Management Plans in place
• Operate in accordance with a NOPSEMA accepted Well Operations Management Plan (WOMP) and Safety Case.

Loss of Materials or Waste Overboard

Our proposed activities offshore that may result in Loss of Materials or Waste Overboard include:

• MODU (drilling) operations
• Vessel operations
• ROV operations

Risks

• Change in Habitat
• Injury / Mortality to Marine Fauna
• Change to Cultural Heritage

Controls

To mitigate or reduce the impacts and risks of our activities we will:

• Implement a Marine Assurance Process
• Implement Offshore Operational Procedures
• Ensure Vessels meet Emissions and Discharge standards

Have your say

We want to hear from relevant persons. Please use the contact form below to get in touch, and feel free to share this website link with any other relevant persons that you are aware of.

What next

We will submit our draft environment plan to the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) for assessment. If you have consulted with us as a relevant person, your input will be considered in improving our EP. Your name will be included in the "sensitive information" part of our plan and not published.  

Summary of Impacts, Risks and Activities

Information Sheet  regarding impacts, risks and control measures.