relevant persons information wheatstone-2 wellhead in situ decommissioning
location and water depth
Wheatstone-2 is located within production licence WA-47-L, approximately 174 kilometres northwest of Dampier Port, and 64 kilometres north of the Montebello Islands, at -19.8137 degrees latitude and 115.3073 degrees longitude. It is at a depth of about 213 metres. The wellhead is about 76 centimetres in diameter and extends about 2.2 meters above the seabed.
The Offshore Petroleum and Greenhouse Gas Storage Act 2006 requires a titleholder to remove all property within the title area that is neither used nor to be used in connection with the operations authorised by the title, or implement an approved alternative. Government policy and guidelines allow in situ decommissioning if it achieves equal or better environmental outcomes compared to complete removal, and if it meets requirements including well integrity and safety.
Chevron proposes leaving the well infrastructure in situ.
EMBA – environment that may be affected
Leaving the wellhead in situ has the potential for environment interactions, known as ‘aspects’.
‘Aspects’ may present environmental risks within the operational area if left unmanaged. Table 1 lists the potential environmental impacts, risks and control measures.
There is no emergency condition associated with leaving the wellhead in situ because it has been plugged and abandoned.
For the purpose of the Environment Plan, the environment that may be affected (EMBA) has been defined as a 500m radius around the wellhead. Corrosion of the wellhead is expected to result in a smaller footprint where seabed disturbance may occur due to the presence and breakdown of the wellhead and release of breakdown product (mostly iron).
marine exclusion zone
Petroleum activities in Commonwealth waters are regulated by the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA). Before petroleum activities can take place, Chevron Australia must develop an Environment Plan which will be assessed by NOPSEMA in accordance with the requirements of the Offshore Petroleum and Greenhouse Gas Storage (Environment) Regulations (2009). These regulations require Chevron Australia to consult with relevant persons whose functions, interests and activities may be affected by the petroleum activity.
The Environment Plan will describe the environment in which the petroleum activity takes place, provide an assessment of the potential environmental impacts and risks arising from the activity, and identify control measures to manage environmental impacts and risks to acceptable levels that are as low as reasonably practicable.
The Environment Plan outline how Chevron Australia has engaged with ‘relevant persons’, whose interests, functions, and activities may be affected and how their feedback has been considered and addressed.
impacts, risks and proposed controls
Summary of impacts/risks and key proposed controls – view Table 1.
We are committed to engaging with Traditional Owners and Custodians, commercial fishers, recreational groups and other relevant individuals and organisations, as required by regulation.
We are seeking your feedback if you consider your functions, interests or activities may be affected based on the information outlined in Table 1.
Let us know if you consider there are any control measures we could implement to eliminate, reduce or avoid an effect.
You can contact us tollfree at 1800 225 195 or leave feedback online below.
If a relevant person asks that their feedback be treated as confidential, Chevron Australia will make this known to NOPSEMA and the information will be kept confidential.
Your feedback during the consultation period will be considered and incorporated into the environment plan.
We commit to keeping you informed and providing responses to any relevant person who so requests.
If you choose to provide feedback on this proposal, Chevron Australia will collect your name and contact details, in addition to your comments, for the purposes of maintaining contact with you and inclusion of your feedback in our submission to NOPSEMA. Provision of this information is purely voluntary, however if you choose not to provide it, we may not be able to contact you in the future regarding your submission. Chevron may transfer your information to NOPSEMA, if required and if you do not identify it as sensitive, and to other Chevron affiliates including our head office based in the United States. For further information regarding how we protect your personal information, and your rights, please refer to our privacy notice.
Figure 1. Location of the wellhead.
Table 1: Summary of impacts/risks and key proposed controls – view here.
- Consultation in the course of preparing an environment plan – NOPSEMA pdf opens in new window
- Environment plan content requirements – NOPSEMA pdf opens in new window
- Environmental requirements – NOPSEMA opens in new window
- Offshore Petroleum Greenhouse Gas Storage (Environment) Regulations opens in new window
- NOPSEMA Assessment Process Environment Plans opens in new window
- Chevron Operational Excellence Management System (OEMS) opens in new window