New Zealand Study

GNS Science

Great South Basin: Well correlations and biostratigraphy

The Great South Basin is one of New Zealand's largest sedimentary basins. Hydrocarbon indications have been found in four of the eight wells in the basin, including a 461 BCF gas-condensate discovery. Modern seismic data has confirmed the potential of the basin for large oil and gas prospects.

This new GNS Science report reviews the lithostratigraphy, biostratigraphy and paleoenvironmental setting of the sediments of the Upper Cretaceous to Palaeogene, and presents new well correlation panels across the basin.

This report represents some major steps forward in our understanding of the basin stratigraphy, including:

• The top of the Hoiho Formation, which contains significant coaly source rocks,
  has been reinterpreted at new depths.
  
  
• The age of the Kawau Sandstone Formation has been revised, and the formation
  may represent two discrete sandstone bodies.
  
  
• The Wickliffe Formation has been informally subdivided into four units based on
  petrophysical log characteristics and biostratigraphy.
  
  
• The Tartan Formation is shown to be equivalent to the Waipawa Black Shale
  Formation in the East Coast Basin. The Formation has been newly identified in
  wells, and the effect of erosion on the formation's distribution has been defined.
  
  
• A new sandstone unit has been defined.

These new findings have a major impact on the understanding of the exploration potential of the basin.

Go to GNS Website

Download PDF flyer here.