3D visualisation of the Mount Isa Crustal Seismic Survey

Legacy product - no abstract available

Legacy product - no abstract available

Case Study: GeoFrame software helps Geoscience Australia provide quick access to 2D and 3D seismic survey data within newly released license/permit in support of successful Australian Acreage Release bidding rounds

In 2006, deep seismic reflection profiling was carried out along six transects across the Mount Isa Inlier. The seismic lines were jointly funded by the Geological Survey of Queensland, Geoscience Australia, the Predictive Mineral Discovery Cooperative Research Centre and Zinifex Pty Ltd. (now Oz Minerals). In 2007, a further three seismic lines were collected by Geoscience Australia and the Geological Survey of Queensland from Cloncurry to south of Charters Towers via Croydon and Georgetown. This paper presents some highlights from the geological interpretations of the seismic lines.

This report presents results from a pilot study conducted within the northern part of the Great Australian Bight, focusing primarily on the Eyre Sub-basin. The aim of the study was to develop and test a methodology for creating petroleum prospectivity maps based primarily on the extent of sealing lithologies. The Eyre Sub-basin provides a good basis for this study due to the good seismic coverage and lithological data provided from eight ODP holes and an Esso petroleum exploration well (Jerboa-1). Well data are used to determine which sequences contain potential sealing lithologies, while seismic data are used to map out the extent and distribution of potential sealing sequences across the study area. The regional extent of sealing units to their first pinch-out is used as a first-order assessment of petroleum prospectivity. Results from Jerboa-1 show that there is a proven oil source and adequate reservoir facies with seal and trap integrity being the major play risks. Mesozoic sediments provide the primary potential sealing units across this region and have greatest thickness across the Eyre Sub-basin. To the west and north of this sub-basin, the distribution of the Mesozoic sediments is discontinuous, resulting in lower sealing potential. Mesozoic sediments are absent within the Eucla Inlier immediately north of the Eyre Sub-basin, resulting in very low sealing potential. Three categories of petroleum prospectivity have been determined in this study. Good prospectivity has been assigned up to the limits of the thick and continuous Mesozoic sediments in the Eyre Sub-basin. Low prospectivity has been assigned to the western Apollo Shelf, reflecting the reliance on relatively thin and discontinuous Mesozoic seals and the poor seal potential of Tertiary age carbonates. The Eucla Inlier is designated as a non-prospective area due to the absence of Mesozoic sediments and any potential sealing units for Tertiary age reservoirs.

Current geological mapping by the Northern Territory Geological Survey is leading to a much better understanding of the surface geology of the Territory. Less well understood is the geometry of the Northern Territory in the third dimension, although this has been predicted by the construction of cross sections (e.g. on recent 1:250 000 geological maps). At shallow depths, the cross sections can be constrained by drilling results, if available, but deeper levels can only be examined by geophysical techniques such as seismic reflection or magnetotelluric profiling, or by modelling of potential field data. Text of paper presented at the NTGS AGES 2002 Workshop, Alice Springs, 26-27 March 2002.

The seismic stacking velocity data in the Otway Basin are a useful dataset for calculating depths and sediment thicknesses. This work presents time-depth relationships computed from unsmoothed stacking velocities and compares these with functions obtained from sonobuoy refraction data and exploration well sonic logs. The comparison suggests that a total sediment thickness over-estimate for the Otway Basin of about 15% can be expected from the depths derived from stacking velocities alone. On the other hand, for sediment thickness calculations down to ~3 s two-way travel time below sea floor, stacking velocity data give comparable depths to those obtained from the sonic logs. A piece-wise formula is offered which scales the time-depth function for the Otway Basin in order to compensate for the depth overestimate inherent in using stacking velocities to calculate total sediment thickness.

The Sedimentary basins of eastern Australia project undertook structural and sequence stratigraphic mapping of a regional grid of seismic reflection data in the Bowen, Gunnedah and Surat Basins (usually 4 seconds two-way travel time data, with about 15,000 line km of data on about 1200 individual seismic lines). The seismic mapping was used to define the interplate and intraplate tectonic events that have helped to create the accommodation space and also to define the stratal geometry of the sedimentary units. Thus, the mapping provided the overall geometry of the basin system as well as the geometry of several of the sequence boundaries, resulting in the development of a new sequence stratigraphic framework for the basins. These results were also compiled into a series of structure contour and isopach maps, which have been used to build a 3D geological map of the Bowen Gunnedah and Surat Basins.

As part of the Australian Government's Onshore Energy Security Program and the Queensland Government's Smart Mining and Smart Exploration initiatives, deep seismic reflection surveys (~2300 line km) were conducted in North Queensland to establish the architecture and geodynamic framework of this area in 2006 (Mt Isa Survey; also involving OZ Minerals and pmd*CRC) and 2007 (Cloncurry-Georgetown-Charters Towers Survey; also involving AuScope). The purpose here is to use new geodynamic insights inferred from the seismic and other data to provide comments on the large-scale geodynamic controls on energy and other mineral potential in North Queensland.