relevant persons information wheatstone well intervention and infill drilling
Chevron Australia is currently undertaking a 5-yearly revision ofthe Wheatstone Well Intervention and Infill Drilling Environment Plan.
Chevron Australia will conduct infill drilling of seven new wells and well intervention activities on the nine existing production wells in the Wheatstone and Iago fields, to maintain gas supply to the Wheatstone liquefied natural gas facility and domestic gas plant.
location and water depth
The activity is located approximately 165 kilometres northwest of the mainland Western Australian Coast, and 40 kilometres northwest of the Montebello Islands. Nine production wells are operational within production licences WA-46-L, WA-47-L, and WA-48-L with coordinates and approximate water depth shown in table 1.
Chevron Australia proposes to drill up to seven additional production wells as part of an infill drilling campaign within the same production licences. The infill wells will be drilled at locations to be determined but within approximately 2.5 kilometres of centrally located manifolds. Indicative locations for six potential future manifolds are listed in table 2.
All activities will occur within an operational area that extends to a 7.5-kilometre radius around the proposed manifolds.
schedule and duration
A mobile offshore drilling unit will drill below the seabed. It will be supported by up to three vessels.
Seven infill wells will be drilled.
Based on an assessment, additional work may occur on the nine existing wells, for repairs, maintenance and data acquisition.
EMBA – environment that may be affected
Drilling activities will have the potential for environment interactions, known as ‘aspects’.
All planned aspects can result in environmental impacts and changes to the environment and may present environmental risks within the operational area, with the exception of underwater sound emission, which could extend approximately 13 kilometres from the source.
Unplanned releases and events might occur while conducting activities.
Table 3 lists the potential environmental impacts and 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 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. Figure 2 shows the EMBA.
Control measures to prevent this event are in place, listed in Table 1, 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.
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, an assessment of the potential environmental impacts and risks arising from the activity, and the identification of control measures to manage environmental impacts and risks to acceptable levels that are 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 – view Table 3.
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 3.
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 wells.
Figure 2: Wheatstone Well Intervention and Infill Drilling EMBA
Table 1: Production well coordinates and approximate water depths – view here.
Table 2: Indicative locations for six potential future manifolds and approximate water depths – view here.
Table 3: 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