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Oil spill model
for NZ
Drilling rights in the ocean surrounding New Zealand are being sold off to big oil companies. Texan oil company Anadarko is set to begin deep sea exploratory drilling this summer off our coasts.
Exploratory drilling is the most dangerous part of oil production and adding the challenges of drilling in very deep water compounds the risks.
A spill from a deep water well could result in oil flowing freely into the ocean for many weeks.
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Day 0
A blowout occurs...
Thousands of barrels of oil could flow into the ocean every day. To stop the spill, a relief well will need to be drilled. Rigs are highly unlikely to be available in New Zealand to do the drilling, so an available rig will have to be located and contracted from overseas...Continue to the next time marker, or explore this map by using the timeline below, or the layers and location tabs aboveDay 4
The spill response is overwhelmed
Maritime New Zealand is responsible for responding to the spill. After only four days, it is likely that their dispersant supplies will have run out and that their three small boats will have been overwhelmed, any additional help will need to come from their overseas partners.Day 14
Auckland beaches on the frontline
The probability map shows the likelihood that a particular area will be impacted by more than 1g/m2 of oil. This threshold is the amount of oil that would require a beach clean up.
In summer, the west coast beaches around the Manukau Harbour are likely to be affected first. In the worst case scenarios (a probability of 5%) beach cleanups may be required just two weeks after the blowout.
Day 23
Relief rig arrives at drill site
Fortunately, in this scenario an uncontracted relief rig capable of drilling in deep water was available on Australia's North West Shelf. After the long journey to New Zealand it has finally reached the drill site.
The complicated task of drilling into the damaged well to perform the necessary kill operations and stop the blowout can now begin.
Day 35
Oamaru penguins on the frontline
The probability map shows the likelihood that a particular area will be impacted by more than 1g/m2 of oil. This threshold is the amount of oil that would require a beach clean up.
In the worst case scenarios (a probability of 5%), Oamaru's local peguins may not only have to contend with a dangerous oil slick out at sea, but oil may also wash up on the beaches where they come ashore each evening.
Day 42
Beach closures increasingly likely
After just 6 weeks, at least 35% of the modelled spills have impacted all west coast beaches from Kaipara Harbour to Raglan.
For some beaches around the Manukau Harbour entrance, the likelihood of oil being present is even higher than this (50% probability).
Day 70
Kaikoura whales under threat
Tourists flock to the coastal town of Kaikoura to see sperm whales. However, after 10 weeks, a vast area of their preferred habitat off the Eastern coast of the South Island could be impacted by the oil spill. In the worst case scenarios (probability 5%), even the beaches of Kaikoura will need to have oil cleaned from them.
Day 90
A wide impact plume
Despite hundreds of kilometers separating the Chatham Islands from the site of the blowout, a spill could impact these islands. After three months, the worst hit parts of the Chatham's have a 35% probability of oil affecting the shoreline.
Combined with the impacts on the prime oceanic foraging grounds of the Chatham Rise, a spill could have disastruous consequences for the unique seabird and marine life of these islands.
Day 120
Ongoing impacts
Although the blowout was stopped over a month ago, oil will very likely continue to drift across the ocean and wash up on the coast. Sadly, this is not the end of the disaster, as the effects of the spill will likely endure for years to come.
To see and read more about the potential impacts, explore the layers and locations tabs. Discover more about deep sea drilling and the science behind the probability maps in the LEARN and THE SCIENCE sections
Hoki (fishery)
Juvenile hoki from both eastern and western hoki stocks mix on the Chatham Rise, making it the most important hoki nursery area in New Zealand. Outside the spawning season, the Chatham Rise is the main fishery area for hoki. Hoki is one of the most valuable commercial fisheries in New Zealand: in 2008 the hoki fishery alone was worth NZ$730 million dollars and hoki was the main export earner for the fisheries sector.References
Map: Deepwater Group, HokiText:NIWA, 20 years of Chatham Rise fish surveys
MPI, Fishery - Hoki (including key bycatch stocks)
Image: © Greenpeace / Sonia SchadwinkelHoki (spawning ground)
Adult Hoki congregate on spawning grounds to reproduce. Their fertilised eggs float up to the surface water and become plankton. Once hatched, the tiny, 4mm long hoki larvae begin feeding on the zooplankton around them.References
Map: Te Ara, Open ocean - Fish larvae and the ocean environmentText: Te Ara, Open ocean - fish larvae and the ocean environmentImage: © Greenpeace / Gavin ParsonsGreen-lipped mussel (spat)
The green lipped mussel is New Zealand’s most valuable aquaculture species: in 2009 mussel exports were worth over $200 million. The aquaculture industry is almost entirely reliant on tiny mussels (called spat) caught in the wild. At least 100 tonnes, representing more than 80% of the mussel spat for aquaculture comes from Ninety Mile beach, where mussel spat is collected after washing ashore attached to seaweed and other debris.References
Map:Alfaro et al., 2011: Green-lipped Mussels in GLM 9. New Zealand Fisheries Assessment Report 2011/48.
Text:Aquaculture New Zealand
Alfaro et al., 2011: Green-lipped Mussels in GLM 9. New Zealand Fisheries Assessment Report 2011/48.
Image: © en.wikipedia / Richard GiddinsSnapper
Snapper is just one of a range of finfish species that make up an important commercial, customary and recreational fishery along the West coast. However, this iconic species is arguably one of the most popular fish targetted by recreational fishermen in the North Island of New Zealand.References
Map: NIWA, Ecosystem influences on snapperText: MPI, Fishery - West coast North Island finfishImage: © Flickr / Brian GratwickeCrayfish (rock lobster)
Crayfish are an important commercial, recreational and Māori customary fishery. Crayfish reach maturity around 5 to 7 years of age. Females carry hundreds of thousands of eggs under their tails for six months until they hatch. As larvae, crayfish drift through the surface waters for six to nine months before returning inshore to settle.References
Map: MPI (NABIS), Annual distribution of Spiny red rock lobsterText: MPI, Rock lobster (crayfish)Image: © en.wikipedia / StemonitisBlue whale
The blue whale is the largest animal in the world. After being hunted to the brink of extinction, only 2,000 remain in the Southern Hemisphere. The area on the map has recently been identified as a possible feeding ground for the blue whale - one of only five such areas outside the Southern Ocean.References
Map: Torres (2013). Evidence for an unrecognised blue whale foraging ground in New Zealand. New Zeal J Mar Fresh: 47, 235-248Text: Te Ara, Whales - blue whales and fin whalesImage: © Greenpeace / Paul HiltonHumpback whale
The humpback whale migrates hundreds of thousands of kilometres between its tropical breeding grounds and its Southern Ocean feeding grounds. Their path takes them along New Zealand's coastlines, which made them a target for whalers until mid last century. Whaling caused the humpback to all but disappear from our waters and since it ended in 1964, the endangered humpback whale has slowly begun to resume its traditional migration route past New Zealand.References
Map: Te Ara, Whales - Whales in New ZealandText: DOC, Humpback whalesImage: © Paul Hilton / GreenpeaceHector's dolphin
At a maximum length of 1.5 metres, Hector's and Maui's dolphins are possibly the world's smallest marine dolphins. These diminuitive dolphins prefer shallow coastal waters and are highly vulnerable to impacts from fisheries and boat traffic. Population numbers of Hector's dolphins have declined by 74% between 1970 and 2009.References
Map: MPI (NABIS), Annual distribution of Hector's dolphinText:DOC, Hector's dolphin
IUCN, Cephalorhynchus hectori
Image: Photograph by James ShookMaui's dolphin
Maui's dolphin is critically endangered - with fewer than 55 individuals estimated to survive in the wild. A major spill could greatly increase the likelihood of extinction for this population, as studies show that for the current population to survive, at a minimum the mortality rate from human causes (e.g. offshore petroleum acitivities and fisheries) must remain less than one individual every 10 years.References
Map: MPI (NABIS), Annual distribution of Maui's dolphinText: Currey et al., 2012: A risk assessment of threats to Maui’s dolphins. MPI and DOC, Wellington.Image: Liz Slooten Otago UniversityNZ fur seal
The New Zealand fur seal, or Kekeno, will hunt for prey along the continental shelf and as far as 200km past the shelf edge. Adult seals may dive almost 200m to catch squid and small fish. Kekeno were pushed to the brink of extinction by hunting in the 19th century and population numbers are slowly recovering. Many places along the east coast are kekeno 'haul outs' - where seals rest after hunting and care for their pups.References
Map: MPI (NABIS), Annual distribution of New Zealand fur sealText: DOC, Facts about fur sealImage: © Greenpeace / Dave HansfordSouthern right whale
Southern right whales used to be so numerous around our coasts that their calls kept Wellington residents awake in the 1800s. However, whaling pushed these animals to extinction around the mainland and the population is only beginning to recover. These large baleen whales come close in to shore to feed.References
Map: Te Ara, Whales - Whales in New ZealandText: DOC, The conservation of whales in the 21st centuryImage: Michaël CATANZARITISperm whale
Sperm whales prefer to live in areas with deep water and can dive to depths greater than 1000m in pursuit of squid, their preferred prey. The main population of sperm whales in New Zealand is found in Kaikoura and it is one of the few places in the world that has an accessible resident population of sperm whales close to the coast.References
Map: Te Ara, Whales - Whales in New ZealandText: DOC, Sperm whalesImage: © Paul Hilton / GreenpeaceBenthic Protection Areas
These are areas of seabed that are closed to destructive bottom-trawling fishing methods. These areas protect seamounts and hydrothermal vents, two habitat types that have been identified by the United Nations as requiring special protection.References
Map: MPI (NABIS), Benthic Protection AreasImage: © Roger Grace / GreenpeaceMarine Mammal Sanctuary
Marine Mammal Sanctuaries are intended to provide a permanent refuge for whales, dolphins, seals and sea lions from activities which may harm them. Although there is not an outright ban on fishing within Marine Mammal Sancturies, certain fishing methods may be restricted, such as the use of set nets.References
Map: DOC, DOC Marine Mammal SanctuariesText: DOC, Marine mammal sanctuariesImage: © Malcolm Pullman / GreenpeaceMarine Reserves
In New Zealand, marine reserves are those areas with the most comprehensive protection for marine biodiversity. No fishing, removal or disturbance of any living or non-living resource is permitted in these areas and dredging, dumping or discharging waste is also banned. In total, just 0.3% of New Zealand's marine environment is protected within marine reserves.References
Map: DOC, DOC Marine ReservesText: DOC, Marine reservesAlbatross
Twelve of the world's albatrosses breed in New Zealand. Albatrosses spend 85% of their lives at sea, travelling thousands of kilometres in a single year.
These majestic birds will travel immense distances from their breeding colonies to find food far out at sea. Birds from the Subantarictic Islands, Chatham Islands and Taiaroa Head will forage along the productive waters of the Subtropical convergence and Chatham Rise. The points on the map represent breeding colonies for three albatross species:
- Taiaroa Head is home to a Northern Royal albatross colony - one of only two places in the world where albatrosses breed on the mainland
- The Bounty Islands is the main breeding site for most of the world's population of Salvin's albatross
- Both the Northern Royal, Chatham and Northern Buller's albatross breed on the Chatham Islands
References
Map: MPI (NABIS), Breeding colonies distribution of Northern royal albatross, Breeding colonies distribution of Chatham albatross, Breeding colonies distribution of Salvin's albatrossText:DOC, Albatrosses
Image: © Greenpeace / Dave HansfordAustralasian gannet
The Australisan gannet (or takapu) breeds in just a few colonies on our coast and offshore islands. Thousands of birds raise their chicks at the same time and parents take turns to forage out to sea to find food for their single chick. Gannets may travel far over the continental shelf in search of prey, making spectacular high speed dives to capture small fish. These birds may become coated in oil as they rest on the water, transferring the oil to the colony and preventing eggs from hatching. If an adult bird becomes coated in oil, it will not survive.References
Map: Te Ara, Gannets and boobies - Gannets: description and habitatText: Taylor, 2000. Action plan for seabird conservation in New Zealand - part B, non-threatened seabirds. DOC, wellingtonImage: x-ophTītī/Sooty shearwater
The tītī, or sooty shearwater, has over 80 breeding sites around New Zealand and its offshore islands. On land, tītī dig burrows for nesting and raising their young. Parents will make short (1-3 days) and long (5-15 days) trips in search of food while caring for their young, sometimes travelling as far as the Antartic Polar Front in search of crustaceans, fish and squid. Tītī (also known as muttonbird) are culturally important as a food resource for Rakiura Māori and chicks are harvested anually.References
Map: MPI (NABIS), Annual distribution of Sooty Shearwater - Normal RangeText: IUCN, Puffinus griseusImage: Marlin HarmsYellow-eyed penguin
Only a few hundred breeding pairs of adult yellow-eyed penguin, or hoiho, survive on the mainland. Hoiho will venture up to 25km out to sea, diving up to 120m deep several hundred times a day to catch small fish. Each evening hoiho return to shore to rest, or to care for their young during the breeding season. Each day hoiho are also a regular sight all around New Zealand, being featured on our $5 dollar note.References
Map: MPI (NABIS), Annual distribution of Yellow-eyed penguinText:DOC, Yellow-eyed penguin/hoiho
Yellow-eyed Penguin Trust
Image: Su Yin Khoo
Hokianga Harbour
Distance from well site: 270 km
The Hokianga area is one of the oldest Māori settlements in New Zealand. According to Te Tai Tokerau traditions it was where Kupe, the Polynesian explorer and navigator, settled after his voyage of discovery from Hawaiki. Giant golden sand dunes at the harbour mouth are a draw card for tourists, who also flocked to the area in the 1950's to see Opo the Dolphin. Recreational and commercial fishing of a wide variety of species is also very common in the harbour.Spill impacts
- Near the harbour mouth in Opononi, 82% of the spill trajectories modelled created surface oiling sufficient to close fisheries (>0.01 g/m2)
- 24% of spills were sufficiently severe that they would require a beach clean up (>1 g/m2) at Opononi
Download the report for a full oiling analysis for Hokianga Harbour and learn about the impact thresholds here: The Science
References
Image: Hokianga dunes by Phillip Capper at en.wikipediaKaipara Harbour
Distance from well site: 210 km
This is the largest estuarine harbour on the West Coast of New Zealand. It is the most important nursery for snapper - 98% of the entire west coast stock comes from Kaipara. It is also an important breeding and juvenile habitat for many other species of fin fish as well as skates, rays and sharks. The harbour provides critical habitat for tens of thousands of migratory birds and is vital to New Zealand's most threatened endemic bird, the NZ fairy tern, as a breeding site and during non-breeding periods.Spill impacts
- 97% of spills modelled reached the Kaipara harbour
- 69% of spills were sufficiently severe (>1 g/m2) to trigger a beach clean up
- An oil slick as dense as 58 g/m2 could affect the harbour, which is more than five times greater than the mortality threshold for birds (>10 g/m2)
Download the report for a full oiling analysis for Kaipara Harbour and learn about the impact thresholds here: The Science
References
Text:DOC, Facts about New Zealand fairy tern/tara-iti
Integrated Kaipara Harbour Management Group
Kelly, 2008. Environmental condition and values of Manukau Harbour. Prepared by Coast and Catchment Ltd. for Auckland Regional Council. Auckland.
Image: Juvenile trevally shot by Richard Ling at en.wikipediaPiha & Muriwai
Distance from well site: 180 km
Piha and Muriwai are two of the Auckland region’s most popular and iconic surf beaches. The Piha surf-break is the site of national surfing championships, while Muriwai is home to one of only three colonies of Australasian gannets on the New Zealand mainland.Spill impacts
Piha and Muriwai are on the frontline for impacts from a spill in Deepwater Taranaki:- Both beaches would have a very high probability (90%) of requiring oil to be cleaned from the shoreline.
- As much as 100 g/m2 could affect Muriwai by the time the flow of oil is stopped - a level ten times greater than the mortality threshold for birds (10 g/m2).
Download the report for a full oiling analysis for Piha & Muriwai and learn about the impact thresholds here: The Science
References
Image: Piha surf shot by Avenue at en.wikipediaManukau Harbour
Distance from well site: 180 km
The Manukau Harbour is a popular recreational fishing area for Aucklanders and is home to several sailing clubs. It is also a highly valuable habitat for many native and migratory wading birds, such as stilts, godwits and herons. In fact, the harbour supports 20% of the total population of New Zealand's wading bird species.Spill impacts
The Manukau harbour would be severely impacted in a spill:- At the harbour mouth, 90% of the spills reached the threshold that would require a beach clean up (>1 g/m2)
- Half of the modelled spill trajectories exceeded the mortality threshold for birds after 76 days
Download the report for a full oiling analysis for Manukau Harbour and learn about the impact thresholds here: The Science
References
Text:Kelly, 2008. Environmental condition and values of Manukau Harbour. Prepared by Coast and Catchment Ltd. for Auckland Regional Council. Auckland.
Image: Langholm Bay by Phillip Capper on FlickrManu Bay, Raglan
Distance from well site: 180 km
Manu Bay is an internationally renowned surf break. It lays claim to the longest, most accessible and consistent left-hand break in the world. The break was featured in the 1966 movie 'Endless Summer' and it has been attracting surfers from around the globe ever since.Spill impacts
- 98% of the modelled spill trajectories affected the surf break at Manu Bay
- In 84% of all spills modelled, oil exceeded the threshold at which a beach clean up would be required (>1 g/m2)
- In the worst case, it would take less than two weeks for large quantities of oil to beach (6.7 g/m2) in Manu Bay
Download the report for a full oiling analysis for Manu Bay, Raglan and learn about the impact thresholds here: The Science
References
Image: surf shot by Jun Kaneko at FlickrNew Plymouth
Distance from well site: 170 km
The Taranaki region is home to rugged coast lines and world-class surfing spots. The city of New Plymotuh has invested heavily in developing an award-winning coastal walkway. Taranaki is also the current infrastructure centre for the shallow water oil and gas industry in New Zealand.Spill impacts
New Plymouth would suffer severe impacts in the event of a spill:- In all scenarios modelled, the coastal waters of the city were impacted by sufficient quantities of oil to close fisheries (>0.01 g/m2)
- In 73% of all spills modelled, oil was sufficiently dense to require a shoreline cleanup (1 g/m2)
Download the report for a full oiling analysis for New Plymouth and learn about the impact thresholds here: The Science
References
Image: Coastal walkway with Len Lye windwand by Pseudopanax at en.wikipediaKaikoura
Distance from well site: 420 km
Off the coast of Kaikoura, a complex system of deep marine canyons supports a great diversity of marine life, including marine mammals and seabirds. The rich waters surrounding Kaikoura attract many species of marine mammal and most notably sperm whales. The town of Kaikoura is reliant on the presence of these large marine mammals for its whale watch industry. Dolphins, NZ fur seals and seabirds such as albatrossess and large petrels are also major attractions for visitors.Spill impacts
Out of all locations on the east coast of the South Island, Kaikoura is likely to experience the greatest impact in the event of an oil spill:- In 91% of spill trajectories modelled, oil was present in Kaikoura in sufficient quantities to create a surface sheen and close fisheries (>0.01 g/m2)
- In the worst case scenario, it would take only three weeks for surface oiling to close fisheries in Kaikoura
Download the report for a full oiling analysis for Kaikoura and learn about the impact thresholds here: The Science
References
Image: Whale dive with Kaikoura in background by Tobias Kierk at en.wikipediaBanks Peninsula
Distance from well site: 260 km
With its many bays and harbours, Banks Peninsula provides ideal habitat for the endangered Hector's dolphin, as well as many other marine animals. To protect these small, coastal water dwelling dolphins from becoming bycatch in set nets, New Zealand's first Marine Mammal Sanctuary was established here in 1988. The peninsula's dramatic cliffs are home to about 75% of the global population of the endemic spotted shag, while it's coastline is home to yellow-eyed and white-flippered penguins. It is also an important area for aquaculture in New Zealand.Spill impacts
An oil spill could severely impact aquaculture and the Marine Mammal Sanctuary at Banks Peninsula:- In the worst case scenario it would take just one week for an oil to impact Bank's Peninsula
- In 44% of the modelled spill trajectories, there was sufficient oil density to close fisheries (>0.01 g/m2)
Download the report for a full oiling analysis for Banks Peninsula and learn about the impact thresholds here: The Science
References
Text:DOC, Banks Peninsula Marine Mammal Sanctuary
Image: Aerial shot of Bank's Peninsula by thinboyfatter at flickrOamaru
Distance from well site: 90 km
Visitors to this historic town are almost guaranteed to see penguins. The world's smallest penguin, the little blue penguin, nests in colonies around the harbour, including under buildings lining the shore. A purpose built visitor centre showcases these birds. Yellow-eyed penguins also breed at sites just south of Oamaru.Spill impacts
Prevailing offshore winds means that there is increasing probability of oil being present further offshore, which would have highly detrimental impacts on the local peguin populations that rely on these waters for foraging:- In addition, 30% of modelled scenarios affected the coastal waters of Oamaru
- In the worst case scenario, a spill could take as little as four days to close fisheries in Oamaru
Download the report for a full oiling analysis for Oamaru and learn about the impact thresholds here: The Science
References
Image: Oamaru by Karora at en.wikipediaTaiaroa Head
Distance from well site: 50 km
The site of the only mainland breeding colonies of Northern royal albatross and Stewart Islands shags in the world. Elsewhere, the Otago Peninsula is also home to yellow-eyed penguins and New Zealand sea lions. Tourism related to these animals is believed to generate at least $100 million dollars annually for Dunedin's local economy.Spill impacts
For the seabirds and marine mammals that make this headland their home, the vast plume of oil across the South Pacific ocean could have disastrous consequences:- In addition, 27% of the modelled spills directly affect Taiaroa Head
- In the worst case, oil could arrive at Taiaroa Head within one week
Download the report for a full oiling analysis for Taiaroa Head and learn about the impact thresholds here: The Science
References
Image: Ulrich Lange at en.wikipediaBounty Islands
Distance from well site: 620 km
The Bounty Island group is a tiny outcrop of granite in a huge expanse of ocean. Despite its size and isolation, this World Heritage Area is teeming with life. It is home to one of the world's largest colonies of New Zealand fur seal and is a major hotspot for oceanic birds, including erect-crested penguins and Salvin's albatrosses. It is also home to the world's rarest species of cormorant, the Bounty Islands shag, of which only 500 or so individuals remain.Spill impacts
- 92% of the modelled spill trajectories reached the islands
- In 84% of trajectories modelled, the amount of oil would be sufficient to create a sheen across the water (>0.01 g/m2)
Download the report for a full oiling analysis for Bounty Islands and learn about the impact thresholds here: The Science
References
Text:DOC, Bounty Islands
Image: Salvin's albatross by JJ Harrison at en.wikipediaChatham Islands
Distance from well site: 960 km
The Chatham's are home to a great diversity of seabirds, including the critically endangered Magenta petrel (Chatham Island taiko), Chatham petrel and Chatham Islands shag, as well as the threatened Chatham albatross, Northern royal albatross and Pitt Island shag. One of the world's rarest shorebirds, the shore plover, forages on the rocky shores of two or three islands. These islands also provide habitat for many marine mammals, including New Zealand sea lions and fur seals, leopard seals, and southern elephant seals. The abundant and diverse bird life and marine life is essential for supporting the livelihoods of the 600 or so permanent residents of the Chatham Islands through fishing, conservation and tourism.Spill impacts
- Oil reaches the Chathams in sufficient quantities to close down fisheries (>0.01 g/m2) in 95% of the trajectories modelled
- The first spill could take as little as 35 days to reach the islands
Download the report for a full oiling analysis for Chatham Islands and learn about the impact thresholds here: The Science
References
Text:BirdLife International
Image: New Zealand fur seal by Avenue at en.wikipediaRomney Prospect
Well depth below sea: 1500 m
Permit: Deepwater Taranaki Permit (PEP 38451)
Permit operator: Anadarko NZ Taranaki Company
Permit owners: Anadarko NZ Taranaki Company (54%); Hyundai Hysco Co., Ltd. (36%), Global Resource Holdings, LLLP (5%), Randall C. Thompson, LLC (5%)
Caravel Prospect
Well depth below sea: 1070 m
Permit: Canterbury Basin Permit (PEP 38264)
Permit operator: Anadarko NZ Taranaki Company
Permit owners: Anadarko New Zealand Company (50%), Origin Energy Resources NZ Limited (50%)
We are sorry this interactive map is not available for small devices. Please make sure to visit this web site on a tablet or personal computer for the full experience.
Learn
The Science
INDUSTRY standard numerical modelling techniques were used for the oil spill trajectory analysis in order to analyse the extent of oil propagation, dispersion and beaching in the event of a deep water at the Romney prospect in the North Island and the Caravel prospect in the South Island.
The numerical model is driven by a global database of meteorological and oceanographic conditions (waves, winds and tide) and reproduces the dispersion of thousands of oil spills during a variety of environmental conditions and scenarios over ten years of data.
With the database of spill trajectories (Fig. 1) generated using this approach we can perform impact assessments, oiling analysis and response time analysis.
Learn more about the methodology and the presented scenario below or download the full technical report or short summaries for both sites here:
From 1000 single spills to 1 probability map
For real world spills like the Rena shipwreck two years ago, deterministic models are used. These models use marine weather forecasts to predict the fate of the spilled oil in real time. For the possible impact of a hypothetical oil spill as shown in this website, probabilistic models are used instead. Probabilistic models run many hundreds or thousands of spill trajectories (see Figures 1 and 2 for a single trajectory) across multiple years of historic marine weather data.
The probability maps are then created from this database of spill trajectories. In the maps, the probabilities correspond to the percentage of the modelled trajectories that exceeded a certain threshold of oil thickness for a given location. This impact threshold or "level of concern" varies for different types of socio-economic or ecological resources of interest.
Scenario for the impact analysis
The impact analysis scenario presented on this website for the Deepwater Taranaki and Canterbury Basin permits are based on the best information that was available at the time of writing the report.
Spill duration: 76 days
A relief rig capable of deep sea drilling must be contracted to drill a relief well and stop the blowout. In the best case scenario a rig will only have to travel from Australia or New Guinea (we estimated 23 days to contract and relocate a suitable rig). The 53 days required to drill a relief well in our scenario is potentially an underestimate, as it is based on a previous shallow water relief well operations at the Montara well, in the Sea of Timor.
Release: 10,000 barrels per day (760,000 barrels in total)
In an area where little or no drilling has taken place, it is virtually impossible to predict what the flow rate of hydrocarbons from a reservoir may be. No industry experts were willing to provide information about what flow rates are expected at the Deepwater Taranaki and Canterbury permit areas. In Taranaki, the Maari oil field has been documented as having wells with natural flow rates of 10,000 bbl/day of crude oil (through a choke of 26%; NZPAM, 2009). Based on this information, we have therefore assumed a worst case scenario of a flow rate of 10,000 bbl/day. A deep sea well needs a high flow rate to be economic, especially given the cost of running a production platform that is specialised for the deep sea environment. Therefore the rate that we have shown may even be an under-estimate of the flow rate that operators are hoping to encounter.
Oil type: medium crude
Before drilling commences an unexplored area, there is uncertainty about the state that hydrocarbons will be in (i.e. gas, condensate or oil). Statements have been made in the media that both the Romney prospect in Taranaki and the Caravel prospect in Canterbury may contain oil. We therefore modelled a medium crude and we verified that this had properties similar to known oil types in Taranaki.
Season: summer
For the website probability maps, we present the results of trajectories modelled during the summer season only, as this is when Anadarko will likely be drilling (see the full report for the winter analyses). The probability maps were therefore based on the 500 trajectories simulated during the summer season. Using 500 trajectories gives less smooth impact probability contours compared to using more trajectories, but does not change the overall results (see page 27 of the full report for further details).
Level of concern: 1g/m2
The level of concern refers to the minimum threshold of oil density shown in the probability maps. We established a minimum level of concern of 1 g/m2 based on the socio-economic impacts at sea and on land that have been defined by National Oceanic and Atmospheric Agency (NOAA) of the United States of America (2013).
Model methodology
The oil spill modelling tools used in this study are public domain software available from NOAA. This includes the General NOAA Oil Modelling Environment (GNOME, Beegle-Krause J., 2001) and the Trajectory Analysis Planner (TAP). A spill was represented by 10,000 Lagrangian elements or particles. The particles’ motion was driven by three main components: oceanic currents, wind and a random diffusion factor set of 100,000 cm2/s.
Oceanographic data
Sea surface currents were extracted from the Global Hybrid Coordinate Ocean Model (Global HYCOM) (Chassignet, et al., 2007). The currents (shown in figure 3) are forced by the US Navy’s Operational Global Atmospheric Prediction System (NOGAPS) which includes wind stress, wind speed, heat flux, and precipitation. The model provides systematic archiving of daily three-dimensional ocean circulation on a global scale with output data archived back to 2003.
Atmospheric data
The sea surface wind data used in the model came from the NCEP/NCAR global reanalysis (Kalnay, 1996) provided by NOAA/OAR/ESRL PSD.
Previous studies have shown that oil tends to spread out in the direction of the wind by typically about 3% of the wind speed (Stolzenbach, et al. 1977). The wind roses in figure 4 show the typical wind speed and direction in the areas that were modelled.
Learn more about the methodology and the presented scenario below or download the full technical report or short summaries for both sites here:
References
- Beegle-Krause, C. J. (2001). General NOAA Oil Modeling Environment (GNOME): a new spill trajectory model, Hazardous Materials Assessment Division, Office of Response and Restoration National Ocean Service, NOAA. International Oil Spill Conference, 865-871.
- Bradley, G. (2012 December 13th). Oil explorer targets deep water. NZ Herald News, Business.
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