1 10 1 https://theses.otagogeology.org.nz/files/original/9ab157748022883d669156956347c62c.pdf 3f094b4597fa4ccf1fa11b47cf62cb55 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Geology theses OU Geology thesis Thesis or dissertation completed by University of Otago Geology students Location WKT (WGS84) The location stored in WKT (WGS84) format MULTIPOLYGON (((174.070746110104 -42.097846706775,174.354811926306 -41.725481753094,175.0229096855 -41.4743803795098,175.182786764833 -41.635287225184,175.298698689571 -41.656856048084,175.786393378181 -41.4345819385547,176.220194151376 -40.9848036585385,176.816067254341 -41.7147376789169,175.521928819304 -42.2842059042345,174.284381302374 -42.3381111532636,174.070746110104 -42.097846706775))) Author last name Last name of the Author Fraser Project type Is it an MSc, PhD, BSc(Hons) or PGDipSci? PhD Advisers Who supervised/advised this student Gorman, A.R. Pecher, I. Abstract The Abstract for this thesis The Pegasus Basin off the east coast of New Zealand's North Island is a frontier basin that hosts a large gas hydrate province. The basin has a large amount of faulting, which has lead to the creation of many interesting and unique accumulations of gas hydrates. In 2009/2010, petroleum industry standard 2D seismic data were acquired across the basin by New Zealand Petroleum and Minerals (a New Zealand government agency) to generate interest in exploration of this basin for conventional oil and gas. This seismic data set presents an unique opportunity to examine the basin's gas hydrate systems with the aim of determining the economic potential of the gas hydrates in the basin while improving our understanding of how observed gas hydrate features were formed. The seismic data were reprocessed to optimise the imaging of features related to gas hydrates. When the data were examined, there were numerous gas hydrate features found, so only a selection are presented in this thesis. With the assistance of seismic attributes, Bottom Simulating Reflections (BSRs) and blanking zones are examined. High-density velocity analysis is used to characterise areas of hydrate (higher velocity) and free gas (lower velocity). The high-density velocity analysis proved to be a very effective technique for examining the structure of gas migration chimneys. Two of the most interesting features identified in the data set include a blank dome shape with a gas chimney at its centre and a text book hydrate/free gas phase reversal that is examined in detail using amplitude vs offset (AVO) and inversion analysis techniques. The model for fluid flow and how the free gas from a chimney at the centre of the blanking zone is converted to hydrate is discussed. The hydrate and free gas phase reversal that is observed was formed by localised fluid flowing from depth into the gas hydrate stability zone (GHSZ). As the BSR becomes shallower, the sea floor deepens at this location. Without a localised fluid flow, the BSR would increase in depth with the increasing depth of the sea floor. Gas hydrate saturation and volumetric analyses were performed for one target. Concentrations were determined using empirical saturation formulae, confirming a potential target. The question of how much gas hydrate potentially is present in the basin, is discussed based both my work and that of others. OURArchive handle The handle from the Otago University Research Archive (OURArchive) <a href="http://hdl.handle.net/10523/7372">http://hdl.handle.net/10523/7372</a> OURArchvive access level Abstract Only Department The department where the student is studying primarily. Geology Named locality Named locality describing the field area location. Pegasus Basin Hikurangi Margin Thesis description Number of pages, maps, CDs, etc. 289 pages A4 Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Identifier An unambiguous reference to the resource within a given context 2017Fraser Creator An entity primarily responsible for making the resource Fraser. Douglas Date A point or period of time associated with an event in the lifecycle of the resource 2017 Title A name given to the resource Seismic characterisation of hydrate and shallow gas systems associated with active margin sediments and structures in the Pegasus Basin, Hikurangi Margin, New Zealand Subject The topic of the resource Geophysics gas hydrates Pegasus Basin Seismic