relevant persons information gorgon umbilical
Chevron Australia, on behalf of the Gorgon Joint Venture, operates the Gorgon Project (Gorgon) in Western Australia.
Gorgon comprises offshore production wells and pipeline infrastructure that gathers natural gas from the Jansz-Io and Gorgon gas fields and transports it to a facility on Barrow Island for processing.
To support the reliability of the offshore gas gathering systems, Chevron Australia will install an additional control and electrical umbilical to the existing feed gas pipeline system that extends between the offshore fields and the Gorgon facility on Barrow Island.
The umbilical will provide electrical power and other functions to the Gorgon gas fields.
Chevron Australia is developing State and Commonwealth Environment Plans for the Gorgon umbilical activity and welcomes feedback from relevant persons.
location and water depth
The Gorgon gas field is located within production licences WA‐37‐L and WA‐38‐L, 130 kilometres off the north‐west coast of Western Australia in water depths of 1,350 metres, and 65 kilometres north‐west of Barrow Island in water depths of approximately 200 metres.
Installation activities will also occur at Whites Beach and within the Gorgon facility on Barrow Island. The Gorgon umbilical will be installed along the existing pipeline route between Barrow Island and the Gorgon fields in State and Commonwealth waters adjacent to the north-west coast of Barrow Island. Water depths in State waters is between 12 and 25 metres and extend out to 130 metres in Commonwealth waters.
Table 1 provides a summary of the installation scope of work and Figures 1 and 3 show maps of the installation areas.
schedule and duration
Installation of the Gorgon umbilical is planned to occur from late 2023/early 2024 to mid-2024.
Table 1 provides details on the timing of the various scope items.
Activities include installing, pre-commissioning and commissioning of the umbilical.
Non-invasive surveys may be conducted before and after installation, including video and geophysical survey techniques.
Installation and support vessels will be used throughout the works.
Chevron Australia plans to install the following:
- An umbilical to supplement power supply in the Gorgon field.
- Pipeline crossings and rock stabilisation as required.
The umbilical will be installed adjacent to the existing offshore subsea Gorgon feed gas pipelines. The shore crossing for the umbilical will be undertaken by horizontal directional drilling from a site to be established approximately 150 metres inland from North Whites Beach, extending under the beach to approximately 550 metres offshore, to avoid disturbing foreshore vegetation and the nearshore marine environment.
On Barrow Island, the umbilical will exit the horizontally directional drilled shore crossing and be installed in a trench for approximately 350 metres prior to connecting to existing infrastructure at the back of the Whites Beach.
Table 1 includes details on the infrastructure to be installed.
EMBA – environment that may be affected
Installation activities can have planned environment interactions, known as ‘aspects’ which may cause environmental impacts or changes to the environment.
There is also potential for unplanned releases and events to occur while conducting installation activities. Potential unplanned events are called environmental risks.
If an emergency condition occurs, the size of the ‘environment that may be affected’, also known as an ‘EMBA’, could increase.
The EMBA is based on the emergency condition’s worst case environmental scenario, which in this case is an unplanned spill event from a vessel collision.
The EMBA has been defined through combining 300 simulations of vessel collisions under different hydrological and meteorological conditions representative of summer, winter and transition seasons in the north-west. Figure 2 shows the EMBA.
Control measures to prevent this event are in place, but Chevron Australia is required to assess this highly unlikely scenario.
In this scenario, cultural, ecological and social values and sensitivities may be exposed to hydrocarbons. These are considered environmental risks because they are not planned to occur.
Table 2 lists potential environmental impacts, risks and control measures.
safe navigation area and marine exclusion zone
During installation of the infrastructure, notices to mariners will be sought, to advise vessels to navigate with caution. A temporary 500-metre exclusion zone will be in place around vessels engaged in installation activities.
There is currently no exclusion zone over the existing infrastructure in the Gorgon gas fields and none will be sought for the Gorgon umbilical.
In accordance with the Offshore Petroleum and Greenhouse Gas Storage (Environment) Regulations 2009 (Cth), the installation of the Gorgon umbilical in Commonwealth waters requires an Environment Plan to be submitted to the National Offshore Petroleum Safety and Environmental Management Authority (NOPSEMA) for assessment and acceptance. These regulations require Chevron Australia to consult with relevant persons whose functions, interests and activities may be affected by the petroleum activity.
Installation activities in State waters and onshore will be addressed in an Environment Plan to be submitted to the Western Australian Department of Mines, Industry Regulation and Safety (DMIRS) in accordance with the requirements of the Petroleum (Submerged Lands) (Environment) Regulations 2012 (WA) and the Petroleum Pipelines (Environment) Regulations 2012 (WA).
Both environment plans will describe the environment in which the installation activities are planned to take place, provide an assessment of the impacts and risks arising from the activities, and identify control measures to manage the potential impacts and risks to levels that are acceptable and as low as reasonably practicable.
The environment plans 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 for installation activities – view Table 2.
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 2.
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: Gorgon Umbilical Installation Map (Onshore and State Waters)
Figure 2: Gorgon Umbilical EMBA map.
Figure 3: Gorgon Umbilical Location Plan
Table 1: Gorgon Umbilical Infrastructure Details – view here
Table 2: Summary of impacts/risks and key proposed controls for installation activities – 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