MBIE is paying Taranaki for an iwi project lead, Fran Davey, and four technical advisors who are iwi members with over a century of combined experience in the oil and gas industry.
Davey said one of the main concerns was to sustain kaimoana.
"It's around protection of mahinga kai so for generations to come there is still kai there, even though this has been inhabited for the last 12 years by an oil production."
She said the agreement enabled Taranaki iwi to see surveys of the seafloor before and after the decommissioning work and helped ease worries about pollution.
"Not being there before, not knowing what was happening was the concern for iwi and for hapū."
Davey said being at the table also meant MBIE was aware of Taranaki iwi's world view and could take cultural perspectives into account.
One of the iwi technical advisors, Geoff Otene, said Te Kāhui o Taranaki's usefulness to MBIE was not limited to cultural advice.
"We have technical people within the iwi who can support MBIE. We are here to support them because we all want a good outcome – in particular a good environment in the future."
MBIE's project director for the Tui decommissioning, Lloyd Williams, said Taranaki iwi was involved soon after the Government took responsibility for the abandoned field in early 2020.
"Our team is working heavily on the technical solutions and their team is providing input on the cultural, environmental and social implications from an iwi perspective - that's the balance we seek."
He said the large ship used as a floating production station over the field, the Umuroa, left New Zealand waters last month.
MBIE was now working with the iwi to gain consents from the Environmental Protection Authority to remove all items from the seabed and plug the wells.
"They will look for evidence that we have had meaningful engagement with all the interested parties including iwi."
He said it was not only about Treaty of Waitangi partnership, but was also best for the project if concerns were raised early and addressed.
"It means our plans are more robust. It gives us more confidence that we are doing the right thing… rather than forge ahead with blinkers on and then hit a speed bump."
Geoff Otene said the iwi hadn't been able to secure a guarantee of work for iwi and hapū members on the decommissioning.
He said there a many companies and consultancies in Taranaki with vast experience in the industry but MBIE was contracting overseas firms.
"I would like to think that the Government or MBIE would ensure this work is shared with local businesses. I think that's been missed for this project… but I think that really needs to be a priority."
Lloyd Williams said the work demanded equipment only available overseas – including a drilling rig to insert concrete 2500 metres under the sea floor to plug the wells.
But he said once in New Zealand the companies often found it best and cheapest to hire locally, especially during Covid-19 restrictions.
Williams says when the Umuroa was demobilised around 170 New Zealanders were employed offshore and another 100 onshore.
"The crew of the boat, the divers, the support boats, the helicopters those are all New Zealand contracts. So there was something like 27 contracts placed with New Zealand companies, most of those in New Plymouth."
Williams said the Government is watching the project as a template for deeper partnership with iwi in the industry.
Taranaki Regional Council's resource management director Fred McLay said the council encouraged MBIE to engage iwi early, and is also watching the decommissioning with interest although the offshore site is outside its responsibility.
McLay envisaged a similar engagement process would be used by the council when large projects within the council's area, such as the Pohokura gas field and the Maui and Kupe gas pipelines, were eventually decommissioned.
"The RMA consent process that we administer we certainly push for early iwi consultation… But there's a bit of work to be done to formalise the process around that – it is a work in progress."
Next summer an underwater robot will dive 120 metres to attach lifting gear for a crane to clear the seafloor at the Tui oilfield, 50 kilometres offshore.
Williams said the drilling rig will then arrive to inject concrete down the eight wells to plug them, with the field likely finally abandoned in the summer of 2022-23.
