OMV New Zealand

New Zealand's Great South Basin - frontier basin exploration

OMV New Zealand this year completed a comprehensive $100 million, five-year exploration programme in the Great South Basin that looks set to broaden the country's understanding of the region beyond just its petroleum potential.

The aggressive project had 75 distinct components. As well as gathering more 2D and 3D seismic data than any previous programme to date, the work also involved a broad suite of geophysical, geochemical, basin modelling, reservoir engineering, metocean, operability and environmental studies.

Marine mammal studies were also carried out in conjunction with the Department of Conservation and Massey University.

The Great South Basin is arguably New Zealand's wildest frontier basin. Large and relatively under-explored, water depths in the area generally exceed 200 metres and can reach 1,500 metres. As well as deep water, the region is known for strong currents, large swells, powerful south-westerly weather systems and occasional icebergs.

OMV and its partners Mitsui E&P Australia and PTTEP New Zealand were awarded three permits covering almost 50,000 square kilometres of the basin in July 2007. The size of the area involved and the limited amount of poor quality existing data meant that the partners had to come up with a new approach if "game changing" advances in knowledge were to be made within the constraints of the initial 5 year permit term.

Rather than adopting a conventional, but easily achievable, linear work programme, OMV says the venture opted for a challenging programme of parallel independent studies and sequential interdependent studies. While more expensive than a conventional programme, the approach taken has delivered technical, operational and environmental data that would have taken "generations" of work using traditional approaches.

And through good planning, a high degree of coordination and tight controls, all projects were completed on time and within budget.

The geoscience work programme included:

  • Two phases of 2D seismic surveying, gathering almost 20,000 line kilometres of data. Both contracts were completed ahead of schedule and under budget.
  • Almost 4,820 square kilometres of 3D seismic were collected over 97 days in the summer of 2011/2012, considerably larger than any other 3D survey in NZ waters.
  • Two high resolution surveys were conducted in shallow water off the Otago and Stewart Island coastlines.
  • Vintage seismic data from a range of industry, academic and research sources were reprocessed throughout the Great South and Canterbury basin.
  • A regional reservoir provenance and thermo-chronology study was undertaken over the Great South and Canterbury basins.
  • A major regional structural geology project deconstructed the present Great South Basin back to its form prior to Cretaceous rifting of the Gondwanan continent.
  • Two phases of regional sequence stratigraphic studies were conducted; the first to define the regional sequence stratigraphic framework of the Great South and Canterbury basins, and the second to define potential source and reservoir sequences within specific sedimentary intervals.
  • Two phases of reservoir engineering studies were carried out to better understand ambiguous well-tests from sub-commercial discoveries in the Great South and Canterbury basins.
  • Total Scanning Fluorescence and Quantitative Grain Fluorescence studies of cuttings data in the Great South and Canterbury basins were commissioned in an effort to identify and fingerprint previously undetected trace hydrocarbons.
  • Additional geochemical and biostratigraphic data were sourced from well cuttings and field studies to increase regional control.

As well as geological studies, the OMV-led programme also involved a heavy measure of metocean studies, including a nine-month placement of a "wave rider" buoy in the GSB. OMV's calibrated metocean modelling was applied to model motion characteristics of various rig types, in order to determine the safest and most efficient rig types could be used in the Great South Basin.

OMV also facilitated an Otago University 3D study of the Southland Current, a major current that separates from the circum-Antarctic current and passes up the east coast of the South Island.

OMV also commissioned a comprehensive Environmental Impact Assessment in consultation with iwi and community stakeholders. Iwi were also contracted to generate a Cultural Impact Assessment that addressed all aspects of the EIA from an iwi and community perspective.

During the most recent 3D seismic survey, the OMV-operated venture trialled DoC's draft marine mammal mitigation procedure, resulting in revisions to the proposed requirements before it was released to industry. Iwi and community stakeholders were also invited to nominate trainee marine mammal observers to help build the capability in New Zealand.

OMV has also contracted specialists from Massey University to conduct necroscopies of any dead marine mammals found in order to test claimed links between seismic activities and marine mortality. OMV intends that this will become a long term study that will benefit all explorers.

OMV's innovative and aggressive exploration programme has rejuvenated interest in Great South Basin exploration, and delivered rapid advancement of knowledge. Although the NZ$ 100 million cost has been high compared to a conventional work programme, it would have taken several "generations" of conventional work programmes to deliver the same advances in knowledge of the area.

The ultimate benefits to industry, iwi, community stakeholders, and the NZ economy will not occur until a GSB discovery has been made and production facilities are commissioned. The impact of a GSB development on employment, infrastructure and education in southern NZ, and the NZ economy in general, cannot be underestimated.

OMV's significant efforts have brought this scenario closer to becoming a reality.

The Energy Project of the Year Award category is sponsored by ITL.