Physical Presence
The Prelude FLNG facility, its supporting subsea infrastructure and additional support vessels all have a physical presence in the operating area. There are a variety of elements which make up the physical attributes and the way they interact with the surrounding environment.
Shell has described the various physical elements of Prelude, their potential impacts and mitigations in the table below.
For a detailed summary, select your area of interest:
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Physical presence
Description
The facility, subsea infrastructure and support vessels will all introduce a new physical presence into the marine environment of the operating area.
Their existence has the potential to impact on the biological and socio-economic environment in and around the operating area.
Potential impacts
Marine animals and birds that live and migrate through the operating area could be impacted by the presence of the facility and support vessels.
Fish species are likely to be attracted to the hull of the facility and the subsea infrastructure. Generally, this is expected to have a positive effect on species diversity and population growth in the area due to the creation of an artificial reef.
Given the location, the number of bird species (threatened or migratory) is likely to be low and limited to individuals only. Birds may choose to rest or roost on the structure.
The remote offshore location of the facility means there is very little human activity in the region apart from oil and gas activity, commercial fishing and shipping. There are no known tourism activities, defence exercise areas, or defence activities within the area. The designated safety zone and water depth mean there is minimal fishing activity of any kind (commercial, recreational, or traditional) in the region.
The closest permanent infrastructure is the INPEX Ichthys project, located 17km south of the operational area. Other petroleum exploration activities are likely to happen in the region, but no aspects of Prelude operations are expected to impact on these activities.
The creation of an artificial reef is likely to have a positive impact in the immediate area around the facility with an anticipated increase in fish diversity and numbers. There is expected to be no credible impact on threatened or migratory bird species as a result of the physical presence of the facility.
Given the size of Prelude in the context of the region’s environment and the remoteness of the location; there will be minimal or slight impacts on the socio-economic environment. Steps have been taken to minimise possible interactions with the facility, equipment and support vessels.
For more information on the impact of Prelude infrastructure and support vessels review the full EP.
Key controls and mitigations
There is a Petroleum Safety Zone around the facility and subsea wells, which exists to reduce the potential interactions with the facility and subsea equipment.
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Lighting
Description
There are two primary sources of artificial light in the Prelude operational area.
- operational and navigational lighting on the Prelude facility and supporting vessels, required for safety
- flaring from both the pilot flares and during intermittent flaring events
These light sources create light spill, which has the potential to impact on marine wildlife and plants, or migratory birds.
Potential impacts
Light spill is known to affect some animals by causing:
- disorientation including attraction or repulsion from other features
- disruption to natural behaviour patterns
- secondary impacts such as reduced fitness and higher levels of predation
The local marine species known to be affected by artificial light include adult female turtles, hatchling turtles and fish. Lighting is known to impact on the choice of nesting location as well as impacting on the orientation of new hatchlings seeking to find the ocean.
Light spill could also result in an increase of food sources for predatory species by encouraging fish populations to aggregate in the light pools.
Birds species are also potentially impacted and may be attracted to the light source. If birds are attracted to the structure there is the potential for collisions with the infrastructure, entrapment in hot plumes, or changes in normal behaviours.
Research suggests the level of lighting on Prelude (similar to that of a quarter moon) and distance from the nesting grounds will mean the potential impact on turtles is acceptably low.
The potential for any animals to gather around the edges of artificial light halos is likely to be highly localised and would not lead to long lasting effects on the local fish population.
Beyond the distance of 5km it has been observed the light was insufficient to cause birds to deviate away from their migration route.
Based on the above and operational experience at the project to date, it has been assessed that there are no impacts from light emissions from Prelude.
For more information on the impact of artificial lighting in the Prelude project operational area review the full EP.
Key controls and mitigations
The facility has been designed so there is no flaring activity during normal operations, which limits the light emissions from flaring and the subsequent impacts.
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Noise
Description
Noise emissions from equipment on the Prelude facility, such as subsea infrastructure and normal operational activities will potentially impact on the surrounding environment. Two modes of operation were modelled for the purpose of understanding the potential impacts of noise on the surrounding environment.
Noise-levels were then assessed alongside marine wildlife behaviour and response data to assess the likelihood of significant effects to the health of animals in the vicinity of Prelude.
Potential impacts
Modelling indicated the potential health impact to marine wildlife would be limited, unless animals were close to the facility for a long period of time.
Surveys indicate there are no sensitive benthic communities in the operational area, and as such there are no expected impacts from noise.
The potential impacts to planktonic communities are expected to be slight, based on the modelling studies conducted by CSIRO.
The closest key ecological feature is 14km away from Prelude. The noise levels at this distance are not expected to have any impact on fish communities at this location. There is a minor possibility that fish communications may be masked by operational noise.
The impact on migratory or threatened species has been assessed as slight, with no significant impacts likely given the distance from key whale migration routes and congregation areas, as well as from turtle nesting habitats. Noise levels and the distance between Prelude and key habitats means impacts will be within acceptable levels.
Overall, levels of noise mean that marine species would have to spend a long time in close proximity to the Prelude facility and subsea infrastructure to be susceptible to any effect. As the operational area does not intersect with any key habitats or migratory routes, any impacts would be to individuals only, and incidents of interactions are considered to be very rare.
For more information on the impacts of noise emissions review the full EP.
Key controls and mitigations
Vessels follow all the requirements of the EPBC Regulations, and Australian National Guidelines for whale and dolphin watching. All interactions with local marine species, including migratory or threatened species, will be within these guidelines.
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Vessel movements
Description
The presence of supporting vessels in the operational area around the Prelude facility may pose a hazard to marine wildlife that live and migrate through the area.
Species considered to be at risk of interacting with vessel movements include whales, dolphins, turtles and whale sharks. However, it is noted that the number of these animals in the operational area has been observed to be low.
A collision between a vessel and marine wildlife could potentially result in the injury or death of the animal involved in the incident.
Potential impacts
There are no important habitats or migratory routes through the operational area. Whales are known to occasionally pass through the area and if doing so are vulnerable, due to their size and the amount of time they spend close to the surface.
The area is also an unlikely habitat for turtles, given the water depths and lack of nesting locations. The presence of any marine turtles within the area, is likely to be limited to individual turtles passing through.
Shell’s understanding and observations of local wildlife behaviour suggests that marine mammals, turtles and sharks are more likely to alter course away from the facility, as well as the stationary or slow-moving vessels in the area.
The marine vessels in the operational area are typically travelling at speeds slower than eight knots. The speed of vessels and watch-keeping onboard makes the likelihood of a vessel strike relatively low. In the unlikely event of a collision, effects to local wildlife would be on an individual scale, rather than at population scale.
For more information on the impact of vessel movements in the Prelude operational area review the full EP.
Key controls and mitigations
Vessels follow all the requirements of the EPBC Regulations, and Australian National Guidelines for whale and dolphin watching. All interactions with local marine species, including migratory or threatened species, will be within these guidelines.
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Seabed disturbance
Description
There may be some disturbance to the seabed in the operational area as a result of ongoing maintenance and potential future installation activities.
Activities which may result in seabed disturbance include:
- Crux Project connections and setup
- replacement of subsea infrastructure
- temporary wet storage of equipment
- part replacements
- miscellaneous inspection, maintenance and repair activities.
Potential impacts
There is generally low sensitivity of the benthic habitat within the operational area, and it is expected that temporarily affected areas will recover quickly as summarised below.
Seabed
The installation of any subsea equipment has a physical impact on the seafloor and associated benthic communities. The anticipated disturbance footprint associated with the installation of future subsea infrastructure, such as with the Crux Project, will be highly localised. For more information about the Crux Project click here.
Similarly, seabed disturbance as a result of inspection, maintenance or repair activities is highly localised and in discrete areas. The amount of specialised equipment required for stabilising subsea equipment is still unknown, however existing operational experience suggests the impact will be minimal.
Water quality
Increased turbidity as a result of operational activities is a possibility.
Impacts to water quality are expected to be highly localised and in short-term sediment plumes. These plumes are likely to result in a slight and temporary decrease in water quality but are not expected to result in any damage or adverse environmental effects.
For more information on the impacts of seabed disturbance in the Prelude project operational area review the full EP.
Key controls and mitigations
- During installation activities, infrastructure is laid on the seabed within the operational area.
- No support vessel is permitted to anchor in the operational area, except in emergency situations or with a specific permit from Shell.
Learn more about Prelude
Prelude Overview
Learn more about the Prelude FLNG facility.
Biosecurity
View Shell’s biosecurity risk assessment and our associated mitigation strategies.
Liquid Discharges
Learn how Shell is managing liquid wastes on Prelude.
Air Emissions
Read about the emissions generated by Prelude and how Shell is managing them.