--> Possible controls on BSR distribution and character in the Pegasus Basin, New Zealand

AAPG Asia Pacific Region Geosciences Technology Workshop:
Gas Hydrates – From Potential Geohazard to Carbon-Efficient Fuel?

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Possible controls on BSR distribution and character in the Pegasus Basin, New Zealand

Michael Macnaughtan 1, Ingo Pecher 1, Lorna Strachan 1, Gareth Crutchley 3, and TAN1808 Shipboard Crew 2,3


1The University of Auckland
2National Institute of Water & Atmosphere (NIWA), Wellington, New Zealand
3Institute of geological & nuclear sciences (GNS), Lower Hutt, New Zealand , New Zealand


April 15-17, 2019 – AAPG Asia Pacific Region Geosciences Technology Workshop: Gas Hydrates – From Potential Geohazard to Carbon-Efficient Fuel?, Auckland, New Zealand

Posted: June 30, 2019

Abstract

This study focusses on an area within a gas hydrate province located across the central Pegasus Basin, New Zealand. The study aims to define previously undescribed controls on natural gas hydrate occurrence within the Pegasus Basin. Two-dimensional (2D) seismic data is used to construct a seismic stratigraphic interpretation of the study area to principally test the hypothesis that there is a stratigraphic control on: 1. BSR distribution and; 2. BSR reflection character within the Pegasus Basin. Five seismic stratigraphic horizons are interpreted across the study area, labelled chronologically from horizon 1 to horizon 5. Interpreted horizons track: 1. discontinuous reflector termination boundaries representing diachronous surfaces; and 2. regionally observed seismic reflectors representing short time intervals of continuous sedimentation conditions that approximately represents an isochronous surface. Interpreted BSRs are categorised according to their occurrence within the stratigraphic record and by their reflectivity character. Mapping overall BSR distribution and distribution of BSR type may show that BSRs preferentially occur within specific stratigraphic intervals. Additionally, the structural control on BSR occurrence is assessed and categorised through observing BSR behaviour across synclinal and anticlinal structures prevalent in the western Pegasus Basin. This study utilises three 2D seismic surveys of varying resolution that spatially overlap each other. This allows for the observation of potentially varying seismic responses at the BSR across different datasets. Furthermore, the recently acquired and interpreted high resolution TAN1808 2D seismic survey used in this study may provide further insights into the nature of BSR reflectivity, particularly around structurally deformed localities within Pegasus Basin.

AAPG Datapages/Search and Discovery Article #90348 © 2019 AAPG Asia Pacific Region Geosciences Technology Workshop, Gas Hydrates – From Potential Geohazard to Carbon-Efficient Fuel?, Auckland, New Zealand, April 15-17, 2019