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Abstract: Hydrocarbon Potential of the Great South Basin, New Zealand

COOK, RICHARD, HAI ZHU, RUPERT SUTHERLAND, STEVE KILLOPS, ROB FUNNELL, Institute of Geological and Nuclear Sciences

The Great South Basin is a Cretaceous rift basin that contains up to 8.6 km of sediment and is of similar dimensions to the Viking Graben, North Sea. Hydrocarbons found in the basin, combined with thermal modelling, show that significant generation of oil and gas has taken place, but the basin is currently under explored. Recent advances in technology now make the water depths of up to 1200 meters in the basin viable for production.

Unlike most of New Zealand, the basin has experienced only minor upper Tertiary tectonics associated with the development of the plate margin through New Zealand. Consequently structures present tend to be large and less complicated than those found in the producing Taranaki basin nearby. The early timing of structure and seal formation is advantageous for hydrocarbon trapping in the Great South Basin. Potential reservoir rocks and seals are widespread throughout the basin and limited drilling shows that fluvial, lower coastal plain, marginal marine and detached lowstand shoreline sands all have porosities of 15-25%. Non-marine and marginal marine rocks provide the source.

A Major review of all industry data from the basin, combined with new geochemical, biostratigraphic, and geophysical studies, have provided fresh insight into the the basin and is being summarised in monograph form. The study has identified untried oil and gas plays and structures, and allows us to model petroleum systems of the basin. It will hopefully provide a new platform for exploration of this prospective basin.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah