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

The Capel and Faust basins lie at water depths of 1,500-3,000 m 800 km east of Brisbane. Geoscience Australia began a petroleum prospectivity study of these remote frontier basins with the acquisition of 2D geophysical data (seismic reflection, refraction, gravity, magnetic, multi-beam bathymetry) across an area of 87,000 km2 during 2006/07. The approach mapped the complex distribution of sub-basins and determined sediment thickness through integration of traditional 2D time-domain seismic interpretation techniques with 3D mapping, visualisation and gravity modelling. Forward and inverse 3D gravity models were used to inform the seismic interpretation process and test the seismic basement pick. Gravity models had three sediment layers with inferred average densities of 1.85, 2.13, 2.31 t/m3 overlying a pre-rift basement of density 2.54 t/m3, itself considered to consist of older basin material evidently intruded by igneous rocks. Conversion of travel times of interpreted seismic horizons to depth domain was achieved using a quadratic function derived from ray-tracing forward modelling of refraction data supplemented by stacking interval velocities, and densities for gravity modelling were inferred from the same velocity models. These models suggest sediment of average velocity 3.5 km/s reaches a thickness exceeding 6 km in the northwest of the area, and for the first time mapped the extent and depth of sediment in these basins. The results of the study have confirmed that sediment thickness in the Capel and Faust basins is sufficient in places for potential petroleum generation.

The granite-greenstone terrains of the Eastern Goldfields Province, Yilgarn Craton, are extremely important as a major Australian gold province. The Kalgoorlie region, in particular, hosts several world class gold deposits. A grid of deep seismic reflection lines was acquired in 1999 to examine the three-dimensional geometry of the major structural features in the region within an area of the Kalgoorlie - Ora Banda region of the Eastern Goldfields Province, Yilgarn Craton. These seismic lines presented an ideal opportunity to further develop our 3D understanding of this highly mineralised granite-greenstone terrain. The seismic grid tied into the earlier 1991 regional deep seismic traverse and the more recent 1997 regional and high-resolution profiles acquired in the region. It covered and area approximately 50 km square that extended to a depth of approximately 35 km (ie the base of the crust in this area). The resulting seismic grid was well suited to the development of a three-dimensional model of the region that could be used to investigate the spatial relationships of the greenstones and the granites. The 3D geological model of this region was built using a 3D modelling software package, GOCAD(r). It was built using surface geological data and geological interpretations of the region's deep and high-resolution seismic reflection profiles. The latter seismic interpretations were constrained by gravity modelling.

Legacy product - no abstract available

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.

As part of Geoscience Australia's Southwest Margin Project, two major marine surveys were undertaken (from October 2008 to February 2009) to investigate the resource potential of deep-water frontier areas on the southwest Australian continental margin. 1. Southwest Australian Margin Regional Marine 2D Seismic Survey (S310) - Areas covered by the seismic survey include the Mentelle Basin, North Perth Basin (Zeewyck and Houtman Sub-basins), Southern Carnarvon Basin and the Wallaby Plateau. Data acquired: 7300 kilometres of 2D seismic (12 second record length, 8 km solid streamer), gravity and magnetic data. In addition to the new seismic reflection data, Geoscience Australia has reprocessed selected open-file industry seismic lines in the offshore Northern Perth Basin (11,700 line km) that provides ties to most wells in the Abrolhos and Houtman sub-basins. 2. Southwest Australian Margin Marine Reconnaissance Survey - The marine reconnaissance survey investigated the geology and marine environments of the offshore North Perth and Southern Carnarvon Basins and the Wallaby Plateau. Data acquired: multibeam swath bathymetry (230,000 km2), gravity and magnetics (25,000 line km), sub-bottom profiler (25,000 line km), geological samples (190 rocks from 53 dredge sites)

In 2007, 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, and a fourth line by AuScope to the northeast of Mt Surprise. Signals were recorded to ~20 seconds two-way travel time (TWT), which equates to about 60 kilometres in depth. The recent lines are among the latest in a series of deep seismic profiles conducted across Queensland since 1980.

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No abstract available

Labuan Basin lies in deep water adjacent to the eastern Kerguelen Plateau. The basin is about 800 km long and 300 km wide and contains up to 4.5 km of sediment. A general lack of geophysical data and geological samples in this remote basin have inhibited understanding of its stratigraphy and crustal origin. Our new seismic stratigraphic interpretation of the Labuan Basin is based on deep multichennel seimic data collected by Geoscience Australia in 1997 during "Rig Seismic" surveys 179 and 180 intergrated with results of Ocean Drilling Program (ODP) Leg 183 (1998-1999)