Accurate seismic velocity model is essential for depth conversion and rock property determination in the context of fluid flow modelling to support site selection for secure storage of carbon dioxide. The Bonaparte CO2 Storage project funded by the Australian Government will assess the carbon dioxide geological storage potential of two blocks in the Petrel Sub-basin on the Australian NW Margin. These blocks were offered as part of the 2009 release of offshore areas for greenhouse gas (GHG) storage assessment. The Petrel Sub-basin is a northwest-trending Paleozoic rift within the southern Bonaparte Basin. The geological reservoirs of interest include the Jurassic Plover Formation and the Early Cretaceous Sandpiper Sandstone. Primary and secondary seals of interest include the Late Jurassic Frigate Formation and the Cretaceous Bathurst Island Group (regional seal). Trapping mechanisms for injected CO2 may include faulted anticlines, stratigraphic traps, salt diapirs and/or migration dissolution and residual trapping. Water depths are generally less than 100m and depths to reservoir/seal pairs range between 800-2500m below the sea surface. All three main types of seismic velocity measurements are available within the area of our study: velocities derived from stacking of multi-channel reflection seismic data; velocities determined in the process of ray tracing modelling of large offset refraction data acquired by the ocean bottom seismographs (OBS) along the coincident reflection/refraction transect, and velocities from well log (sonic, vertical seismic profiling and check shot) measurements.

In the search for deposits of radioactive minerals in Australia the area of the Barrier Ranges appears especially worthy of investigation on geological grounds because it is composed of highly mineralised pre-Cambrian rocks. Mines in this area comprise the major producing mines along the main Broken Hill lode, one developed mine of less importance (the Pinnacles), and a number of small silver, lead and copper mines scattered over the surrounding district. The present report deals with the results of a reconnaissance radio-active survey performed by the Geophysical Section of the Bureau during July and August, 1950. The work was confined to the smaller mines, attention being directed, in the first instance to the mines from which radio-active museum specimens were stated to have come. At each mine the following tests were performed: tests on dumps and residues to discover whether any quantity of stone carrying a significant content of radio-active minerals had been broken during mining operations, tests on accessible exposed faces, and tests on rocks surrounding the mines. The tests were made with portable Geiger-Mueller rate-meters. Readings taken are quoted as multiples of background count, which has been considered as a constant characteristic of the instruments, rather than as the general reading obtained on country rock in the area. In most areas these methods of defining background would lead to the same result. As mentioned later, however, in the Broken Hill area this is not the case. Generally, the schists and gneisses on this field are definitely radio-active, and a true background reading, indicative of the complete absence of radio-active minerals, is obtained only on basic rocks. A reconnaissance survey was also made over the Euriowie tin field. Tests were also made around felspar quarries at Egebeck.

A brief geological examination of this deposit was made by the writer and D.N. Smith between 18th and 20th June, 1952. The deposit had been previously examined in 1951 by J. Daly of the Geophysical Section, Bureau of Mineral Resources, and by J.C. Lloyd of the N.S.W. Mines Department and the results of their investigation were available for reference. The radioactive area examined during the present investigation was an area of about 1/4 square mile of the volcanic flow in the north-eastern corner of portion 39. Samples of the quartz veinlets and of the volcanic rocks were collected, and tests carried out with the Laboratory Geiger counter in Canberra indicate that both are radioactive and that the radioactivity is slightly greater in the sample from the quartz veinlets.

The boring campaign carried out during 1950 by the Petroleum Technology section of the Bureau proved the existence over an area of 25 square miles in the Oaklands-Coorabin coalfield of approximately 793,000,000 tons of coal with an average calorific value of 9150 B.Th.U. per 1b. Thickness of the coal intersected in the bores ranged from 18 to 59 feet and depth to the coal from 186 to 565 feet. This report comprises detailed coal analyses, notes on the geological results, and recommendations for future boring.

Two methods are outlined in this report. The first, is a method intended for the determination of porosity of consolidated sediments. The method is applicable to those sediments included in rotary drill cores and hand specimens of rock collected in the field. The second, is a method intended for the determination of permeability. It is applicable to suitably sized samples of rocks and any other substances whose constitutions permit of their being treated by the procedure set out in this method, subject to their own inherent limitations relative to this method. This report provides a detailed description of each of these methods.

In conjunction with an engineer of the Works and Housing Branch, a brief examination of the limestone deposits at White Rocks was made on 2/11/50 to determine their suitability as a source of road-metal and aggregate. The location and characteristics of the limestone deposits are described in this report. The northern and southern outcrops are described in some detail, and recommendations are made for further investigation.

This statement gives the results of a scout drilling campaign conducted by the Bureau at the Kirby's Hill Area of the Western Coalfield of New South Wales. The area investigated comprises approximately 200 acres of the parish of Cullen Bullen in the County of Roxburgh. At Kirby's Hill itself a maximum of about 300 feet of Coal Measure rocks rests on Upper Marine beds, and this is one of the most westerly exposures of the Upper Coal measures. The purpose of scout drilling was to determine the suitability of the Lithgow and Irondale Seams for open cut exploitation.

Attention has been directed to the cobalt workings at Carcoar as a possible source of radioactive minerals in two ways. During testing of museum specimens for radioactivity, it was found that cobalt ore from Carcoar was strongly radioactive. Also, the occurrence of uranium in the cobalt ores was reported by Mr. McKillop, formerly a land holder in the area, who submitted a copy of a report signed by Professor T.H. Laby, certifying the presence of uranium in samples examined by him, and at a later date, a sample containing an uranium mineral. A brief visit was paid to the area in 1948, and the presence of strong radioactivity on dumps was confirmed. A more extensive survey of the area was, therefore, undertaken by geophysicists during 1949-50 and 1950-51. This report gives an account of the geophysical operations carried out in the vicinity of the Carcoar cobalt workings and describes the results of these investigations.

Like many of the basins along Australia's eastern seaboard, there is currently only a limited understanding of the geothermal energy potential of the New South Wales extent of the Clarence-Moreton Basin. To date, no study has examined the existing geological information available to produce an estimate of subsurface temperatures throughout the region. Forward modelling of a basin structure using its expected thermal properties is the process generally used in geothermal studies to estimate temperatures at depth in the Earth's crust. This process has been validated for one-dimensional models such as a drill hole, where extensive information can be provided for a specific location. The process has also seen increasing use in more complex three-dimensional (3D) models, including in areas of sparse data. The overall uncertainties of 3D models, including the influence of the broad assumptions required to undertake them, are generally only poorly examined by their authors and sometimes completely ignored. New methods are presented in this study which will allow estimates and uncertainties to be addressed in a quantitative and justifiable way. Specifically, this study applies Monte Carlo Analysis to constrain uncertainties through random sampling of statistically congruent populations. Particular focus has been placed on the uncertainty in assigning thermal conductivity values to complex and spatially extensive geological formations using only limited data. These geological formations will typically consist of a range of lithological compositions, resulting in a range of spatially variable thermal conductivity values. As a case study these new methods are then applied to the New South Wales extent of the Clarence-Moreton Basin. The structure of the basin has been built using Intrepid Geophysics' 3D GeoModeller software package using data from existing petroleum drill holes, surface mapping and information derived from the FrOGTech SEEBASE study. A range of possible lithological compositions was determined for each of the major geological layers through application of compositional data analysis, using data from deep wells only (>2000 m). In turn, a range of possible thermal properties was determined from rock samples held by the New South Wales Department of Primary Industries and analysed at the Geoscience Australia laboratories. These populations of values were then randomly sampled to create 120 different forward models which were computed using SHEMAT. The results of these have been interpreted to present the best estimate of the expected subsurface temperatures of the basin, and their uncertainties, given the current state of knowledge. These results suggest that the Clarence-Moreton Basin has a moderate geothermal energy potential within an economic drilling depth. The results also show a significant degree of variability between the different thermal modelling runs, which is likely due to the limited data available for the region.

During an inspection of limestone deposits at White Rocks on 2/11/50, samples of weathered granite were collected from a quarry on the eastern side of the Queanbeyan-Cooma road, about 150 yards south of the two-mile peg. This quarry is in the Queanbeyan Clay Deposit described by W.G. Woolnough in departmental reports dated 17/2/28 and 20/6/28. If the rock can be economically crushed and worked, it may be suitable for the production of sewer-pipes and other impervious ware. The samples, reserves, and suitable uses for the granite are described in this report.