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.

The beach sands on which investigations were carried out, were mainly from beaches along the eastern coast of Australia and from islands adjacent to this coast. A high percentage of the mineral grains of the heavy mineral fraction in these sands have grain sizes within the range -100 to +200, referred to British Standard Sieves. The grain size of the minerals, combined with the fact that the grains are quite well rounded, makes the heavy mineral sands an ideal subject for separation using the inclined method with the Isodynamic Separator. The use of this method, and the results obtained, are described in this report.

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.

In January, 1951, samples of radioactive minerals stated to have been collected in the Mt. Kavanagh (Cavenagh) area, Central Australia, were submitted to the Bureau by Mr. Norman Ashmore. Two radioactive minerals were present, one apparently allanite, and the other a strongly radioactive mineral of composition similar to betafite. The opportunity was taken of the presence in Alice Springs of the geophysical party destined for Rum Jungle and the geological party destined for Maranboy to make a brief inspection of the area. Two days were spent in the area. This report gives an account of the investigations and their results.