Regional Paleogeography and Implications for Petroleum Prospectivity, Taranaki Basin, New Zealand

The Taranaki Basin, located predominantly offshore of western North Island, is currently the only sedimentary basin in New Zealand with active hydrocarbon production. The basin has had a complex history from the Late Cretaceous through to the Neogene, encompassing rifting, passive subsidence, compressional tectonics related to the evolution of the Australia-Pacific plate boundary and late back-arc rift phases.

As part of ongoing research into New Zealand’s petroleum resources, a regional reassessment of the paleogeographic evolution of the Taranaki Basin and surrounding areas has been undertaken, the results of which are presented here. This forms part of a larger project investigating the Taranaki Basin through new basinwide seismic mapping, biostratigraphy, facies analysis and basin modelling.

A set of 31 maps spanning the Late Cretaceous to present day have been produced, which synthesise paleobathymetric and paleofacies data. These maps expand, both in number and geographical area, on those from previous studies and incorporate significant new data. Inputs include map data from previous studies, a new compilation of biostratigraphic and bathymetric data from >200 wells in and around the Taranaki Basin and compilation of outcrop data from areas surrounding the basin. Perhaps the most important addition in this study is the use of seismic attribute and facies mapping, leading to better delineation of depositional elements, both in areas covered by 3D data and in sparser regional 2D surveys.

The study was carried out using GIS, allowing for the capture of significant metadata relating to features such as wells, faults, paleofacies and paleobathymetry. The maps were chosen to provide at least one paleogeographic reconstruction for major sequences bounded by regionally mapped seismic reflectors. Where possible, additional maps were constructed to capture major changes in facies or paleobathymetry within sequences.

These new paleogeographic maps provide improved control on crucial elements of the petroleum system, particularly on the distribution of potential reservoir facies, such as Cretaceous-Paleogene marginal- to shallow-marine facies and Miocene-Pliocene submarine fan systems. These maps capture the most important aspects of the tectonic and sedimentary evolution of the Taranaki Basin, and form the basis for ongoing more detailed paleofacies mapping, basin modelling studies and evaluation of regional petroleum exploration play concepts.

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California