Imaging the Convergent Overprint of a Passive Margin from 2-D and 3-D Seismic Reflection Data, Southern Taranaki Basin, New Zealand
The Taranaki Basin is currently the only hydrocarbon producing basin of New Zealand. The southern part of the basin has undergone a complex sedimentary and tectonic history since the onset of deformation associated with the evolving Pacific and Australian convergent plate boundary. Current knowledge about the associated sedimentary development and facies distribution is dominantly based on investigation of relatively sparse well data and selected 2D seismic lines. Here, we map the distribution of seismic facies using seismic attributes on a regional grid of 2D and 3D seismic reflection surveys with the objective of improving the present understanding of structural development, regional tectonics, sequence stratigraphic history, paleodepositional environments and overall hydrocarbon potential of the area.
Our general workflow involves seismic interpretation, attribute creation and assessment of their discriminatory significance via crossplotting and Principal Component Analysis (PCA), facies classification using Artificial Neural Networks (ANN), horizon and proportional slicing, and gridding of 2D attribute extractions.
Integrated 2D-3D attribute maps show the sedimentary response of convergence and uplift of the hinterland and highlight the components of the eventuating regressive megacycle. Convergent tectonics indicative of foreland basin development commenced as early as Late Eocene/Early Oligocene, which is corroborated by growth strata within Turi Formation equivalents in the footwall of the Manaia fault and contemporary formation of the Waiokura syncline. From Late Oligocene through the Miocene, shelf progradation was directed to the west and northwest as a direct result to convergent activity on the Manaia and Taranaki Fault. Early Miocene basin-floor fan deposits of the Moki Formation are imaged showing multiple generations of fan lobes, which are cannibalized by channel systems during subsequent progradation. The Mid Miocene sequence contains well developed channel systems of the Mount Messenger Formation. These channels are traceable over tens of kilometres showing well defined lateral accretion packages and coarse grained basal lag deposits. The delineation of these features and correlation of attribute responses with wireline logs give firm constraints on location and extent of Miocene reservoir facies in southern Taranaki basin.
AAPG Search and Discovery Article #90090©2009 AAPG Annual Convention and Exhibition, Denver, Colorado, June 7-10, 2009