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Cook Strait

Location: Cook Strait, New Zealand

Type of Project: Oil Spill, Numerical Modeling

Client: OMV New Zealand Ltd, New Zealand

ASR Projects- Cook Strait

From left to right: 3DD Model output showing the instantaneous tidal currents during slack flow in the Strait Narrows, 3DD Model output showing the instantaneous sealevel during slack flow in the Strait Narrows.

Project Overview:

ASR Ltd. Conducted an oil spill trajectory modelling study for OMV New Zealand Ltd as part of their planned development of the Maari Field. The site is located on the continental shelf, approximately half way between Cape Egmont in the north and Farewell Spit in the south at approximately 100 m depth. This region is often referred to as the Greater (or Western) Cook Strait.

Project Outcomes:

In order to assess the potential impact from an oil-spill at Maari, OMV commissioned ASR Ltd to undertake an oil-spill trajectory model study of the region. The aim of the trajectory study was to assess the likely dispersal patterns and the potential for beaching in the unlikely event that a spill would occur.

The study developed a statistical probability map of beaching, the time necessary for oil to beach under a range of realistic spill scenarios, as well as the associated volumes. Annual and seasonal budgets for two products were considered. The first is the Maari crude oil in volumes of 10 m3, 100 m3 and 7000 m3. The second was diesel oil in volumes of 10 and 100 m3.

The oil spill trajectory model established for the Maari development using POL3DD, a Lagrangian dispersal model, which treats all of the relevant physical processes including advection, wave action, vertical and horizontal diffusion, buoyancy, dissolution, evaporation as well as the beaching of spills. The model was driven by tidal hydrodynamics and wind-driven surface currents over the entire model domain.

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