Re-use of offshore infrastructure and platforms: assessing value to communities, industry and environment (innovation fund)

Picture of offshore platform in Taranaki

We investigated the environmental, social, and economic implications of decommissioning offshore oil and gas structures in Taranaki.  

Project status: Completed

Project leader: Elemental Group Limited

Research partners:  Victoria University of Wellington, ERM New Zealand Ltd, Callaghan Innovation

Collaborating parties: Offshore oil and gas operators who contributed environmental monitoring data (Beach Energy, Anadarko, OMV, Shell Taranaki Ltd, Tamarind Taranaki Ltd, New Zealand Oil and Gas), the Department of Conservation, and NZ Māori Tourism.


The five offshore oil and gas installations in Taranaki, New Zealand are approaching the end of their economic field-life and are currently expected to be decommissioned between 2020 and 2046.

New Zealand oil and gas operators apply for approval to decommission through the marine (EEZ) or resource consenting process (RMA) depending on whether the structure is in territorial or EEZ waters. The government is in the process of developing a national framework for decommissioning.

There are three main decommissioning options:   complete removal, partial removal or leaving the installations where they are.  Our research assessed the social, economic and environmental impact of each option.

Impact of offshore structures on benthic species

We examined monitoring data relating to historic benthic invertebrate (such as worms and small crustaceans).  We used statistical techniques to analyse whether presence of the oil and gas structures was influencing benthic communities.  Fish were not assessed due to safety restrictions working close to offshore structures, but international studies on the use of offshore structures by fish species were reviewed.  

We concluded that there is no evidence that benthic communities are being either positively or negatively affected by the presence of the structures at the monitored sites. International evidence suggests there may be benefits for fish species if parts of offshore structures are left place rather than removed as these structures may provide additional habitat in an otherwise quite uniform and flat offshore seabed.

Diversity of marine mammals

We reviewed the Department of Conservation’s records of marine mammal sightings in the Taranaki bight between 1900 and 2016.   The records show that 25% of the world’s 80 known cetacean species live in the South Taranaki Bight.

Cost benefit analysis

Our research includes a cost benefit analysis of each of the decommissioning options.  Companies that specialise in the decommissioning of oil and gas infrastructures could benefit by up to $1.28 NZ billion if all structures are removed.  We estimate that international companies would do approximately 70% of decommissioning work and New Zealand companies approximately 30%. Restoration of the marine environment would cost oil and gas operators in the billions of dollars but the Crown would contribute in the form of tax repayments in the millions of dollars.  There may be minor benefits for commercial fishing companies in Taranaki because removal of the infrastructure and exclusion zones may lead to operational efficiencies and possible increase in fish catch of 1.3%.

Participation in decision making

We held hui with representatives from Ngati Mutunga, Te Atiawa, Ngaruahine and  Ngati Maru to listen to their views on the re-use of offshore infrastructure.  Regional iwi we met with indicated a clear desire to be equal partners in discussions about decommissioning planning for offshore structures.  They want oil and gas operators to discuss decommissioning plans on a case by case basis with mana whenua.

Other than one local diver group, recreational fishing groups and other community groups showed very little interest in engaging on the issues.  We analysed media reports about decommissioning and ran an extensive public survey.  We concluded that there is limited public awareness or engagement in the implications of different decommissioning options. 

We recommend that the oil and gas industry convene a community panel to work with each operator on specific decommissioning plans.  This may give rise to a better understanding of the issues among the community and a coordinated regional decommissioning strategy.

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