gorgon and jansz-io drilling, completions and well maintenance
Chevron Australia, on behalf of the Gorgon Joint Venture, operates the Gorgon Project (Gorgon) in Western Australia.
Offshore facilities include 29 production wells in the Gorgon and Jansz-Io gas fields. The produced gas from the wells is gathered at several subsea structures installed at each field and transported via pipelines to the Gorgon Gas Facility on Barrow Island.
From the facility, gas is processed for export as liquefied natural gas (LNG) or piped to the mainland for WA domestic gas users.
We are now undertaking a routine revision of the Gorgon and Jansz-Io Drilling, Completions and Well Maintenance Environment Plan (EP), as required by Commonwealth regulations, to ensure it remains current.
The EP accounts for well maintenance activities, as well as contingency for re-drilling of existing production wells and plug and abandonment activities.
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 WA, and 65 kilometres north-west of Barrow Island in water depths of approximately 200 metres.
The Jansz-Io gas fields are located within production licences WA-36-L, WA-39-L and WA-40-L, approximately 200 kilometres off the north-west coast of WA in water depths of approximately 1,350 metres.
All activities will occur within an operational area that extends to a 5-kilometre radius around the well locations shown in table 1.
In 2024, Chevron Australia plans to undertake well intervention activities on four wells in the Gorgon and Jansz-Io gas fields.
The EP will also account for activities that are not currently planned but may occur including re-drilling of existing wells, other well interventions, well maintenance and repairs, data acquisition and plug and abandonment.
A mobile offshore drilling unit (MODU) or intervention vessel and up to three support vessels will be used to complete these activities.
schedule and duration
Drilling, completions and well maintenance activities may be required throughout the life of the Gorgon offshore facilities.
These activities may be undertaken at any time of year and would take approximately 65 days to complete.
marine exclusion zone
EMBA – environment that may be affected
As part of our environmental assessment and consultation process, we create an EMBA map to demonstrate the largest geographical area that may be impacted by planned events or unplanned emergency events.
Figure 2 shows the operational area for the proposed activities, as well as the broader EMBA which is based on a worst-case environmental scenario, which in this case is an unplanned release event from a loss of well control.
The EMBA has been defined through combining 300 simulations of loss of well control under three different hydrological and meteorological conditions. This means that in the highly unlikely event an unplanned release does occur, the entire EMBA would not be impacted.
If there were an unplanned release, cultural, ecological and social values and sensitivities may be exposed to hydrocarbons.
Table 2 summarises the potential impacts/risks and proposed controls to manage these to levels that are acceptable and as low as reasonably practicable (ALARP).
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 EP 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 us to consult with relevant persons whose functions, interests and activities may be affected by the petroleum activity.
Following consultation, we will develop an EP which will:
- describe the environment in which operations are planned to take place;
- include an assessment of environmental impacts and risks arising from the activities;
- identify control measures to manage the potential impacts and risks to levels that are acceptable and ALARP; and
- outline how Chevron Australia has engaged with relevant persons and how their feedback has been considered and addressed.
Before activities can commence, the EP must be assessed and accepted by NOPSEMA.
We are now seeking your feedback and input if you consider your functions, interests, or activities may be affected based on the information summarised in Table 2. We encourage you to provide details of any additional aspects or control measures or to ask for further information or consultation.
You can contact us toll free on 1800 225 195 or leave feedback online below.If a relevant person requests their feedback be treated as sensitive and confidential, Chevron Australia will make this known to NOPSEMA.
The feedback we receive during consultation will be used to inform and enhance the EP before it is submitted to NOPSEMA for assessment.
We commit to keeping you informed and providing responses to any relevant person who so requests.
If you choose to provide feedback, Chevron Australia will collect your name and contact details, for the purposes of maintaining contact with you and including 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. Chevron may transfer your information to NOPSEMA if required and, if you do not identify it as sensitive, to other Chevron affiliates including our head office in the United States.
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