This report refers to an offshore aeromagnetic survey over the continental shelf of south-eastern Australia, from Gippsland in the east, through Bass Strait, to Encounter Bay and Kangaroo Island in the west. The survey was carried out for Haematite Explorations Proprietary Limited by Aero Service Limited during the period 17th September to 21st December, 1961. A previous reconnaissance aeromagnetic survey carried out by the same contractor over Bass Strait in December, 1960, had indicated the existence of deep Tertiary-Mesozoic sedimentary basins. The objective of the later survey was to delineate these basins and to extend the investigation farther westward with a view to selecting areas for marine seismic surveys. 17,945 miles of aeromagnetic traverse were flown and the results of the operation are presented as contoured maps of total magnetic field intensity and of interpreted basement depth. As a result of the survey, several areas of deep sedimentation were delineated in sufficient detail to allow for the planning of subsequent investigation by marine seismic surveys.

Wongela GeoIilysical Pty Ltd conducted a helicopter gravity survey for the French Petroleum Company (Australia) Pty Limited in northern South Australia during the period 22nd August to 21st November, 1963, and established 2204 new gravity stations. The area surveyed is in Oil Exploration Licences Nos 20 and 21, and originally covered 34,000 square miles. This area was increased to 35,500 square miles to fill in a gap between the subject survey and the Delhi Alton Downs survey farther east. The work is tied to previous reconnaissance gravity surveys in Central Australia and completes the gravity coverage of the Simpson Desert. The survey was carried out to determine the extent of Palaeozoic sedimentation in the area and in particular to determine whether Amadeus Basin sediments extend into the survey area. These sediments are masked in the area by relatively flat-lying Mesozoic and more recent sediments. The younger sediments have much the same thickness and density throughout the survey area, and for this reason their contribution to variations in the anomaly field is small. Hence the variations in the anomaly field are thought to be due mainly to density contrasts in the basement and between the basement and pre-Mesozoic sediments. The survey results have defined some major geological structural units. These are described and discussed individually in the text of the report. Of particular interest is the Dalhousie Gravity Depression which probably represents a large area of pre-Permian sedimentation, about 8000 feet in thickness. To the east of this feature is a platform area which was probably fairly stable and high standing dUring pre-Permian time in which period it received only a thin cover of sediments. It is probable that since early Permian times the area has been depressed relative to the area of the Dalhousie Gravity Depression and the area farther west, and has received extensive Permian and Mesozoic sedimentation, the sediments thickening towards the east.

Mount Salt No. 1 Well was located approximately twelve miles south-west of Mount Gambier in the South Australian part of the Otway Basin. The well was drilled by Reading and Bates (Australia) Pty Ltd for Oil Development No Liability, to a total depth of 10,044 feet. DrillIng commenced on 9th May, 1962 and was completed on 21st September, 1962. A full programme of logging, testing, and coring was undertaken. After passing through about 3260 feet of Oligocene and Eocene-Palaeocene sediments, the well entered a thick sequence of Upper Cretaceous sands, siltstones and clays that persisted to total depth. The upper part of this section has been correlated with the (?) Paaratte Formation, and the well bottomed in either basal Upper Cretaceous or uppermost Lower Cretaceous marine or brackish strata that probably correlate with either the top of the Waarre Formation or the Flaxmans Beds of Flaxmans No. 1 Well. The base of the Upper Cretaceous is not clearly defined, and no definite conclusions as to the correlation of the section below the Knight Group (? 590 to? 3260 feet) have been advanced. Mount Salt No. 1 Well was drilled to test the petroleum potential of Cretaceous sediments in a closed structure detected by photogeology and proved by a structure drilling programme. Traces of crude oil were detected by core analysis and a show of gas was recorded from the interval 9830 to 9848 feet. Five drillstem tests were attempted but only one, over the interval 9813 to 9892 feet, was successful, obtaining 4070 feet of highly saline water. The stratigraphic drilling operation at Mount Salt No. 1 was subsidized under the Petroleum Search Subsidy Act 1959-1961, from 980 feet to total depth.

A gravity survey of 3883 stations covering an area of 4000 square miles was conducted in southern Queensland and northern South Australia by GeophySical service International's Party 662 for Delhi Australian Petroleum Ltd, from July to December. 1962. Most of the gravity stations were approximately one-half mile apart but 824 were one-quarter mile stations. In general, stations wel'e set in a four by fifteen-mile grid, although in some areas, particularly in the south-eastern portion of the survey. closer control was established. The survey was designed to determine the major gravity anomalies in the prospect area and to seek structural leads in an area almost devoid of outcrop. Fifteen gravity anomalies of significance were discovered eight of which are related to basement topography while the remainder indicate features within the sedimentary section. Computed sedimentary thicknesses ranging from 3500 feet to 21500 feet were obtained. Seven major anomalies related to basement features are recommended for further detailed geophysical investigation. In this summary, the results of the survey are presented on the Bouguer gravity map at a scale of 1:250 000. The geophysical operation undertaken in the Alton Downs area of the Great Artesian Basin. Queensland and South Australia, was subsidized under the Petroleum Search Subsidy Act 1959-1961.

A reconnaissance aeromagnetic survey was conducted in 1961 by Aero Service (Bahamas) Ltd for Delhi Australian Petroleum Ltd. The survey covered a part of the Great Artesian Basin in the north-eastern corner of South Australia and adjacent areas in Queensland (see Fig. 1). The project area lies within Oil Exploration Licences Nos 20 and 21 (South Australia) and Authorities to Prospect Nos 66 P and 67 P (Queensland). The purpose of the survey was to determine the depth and configuration of the pasin within the survey area and to infer structural conditions at the basement surface which, if reflected in the overlying sedimentary section, could provide conditions favourable for the accumulation of oil or gas. The survey was carried out using a Gulf Research and Development Company Mark III total field magnetometer of the self-orienting saturable core fluxgate type mounted in a tail boom installation on a Piper Apache aircraft. Navigation was by visual reference to 163,360 and 1253,440 scale uncontrolled photo-mosaics and the actual flight path was recorded by an Aeropath 35 mm continuous strip film camera. A Gulf Research and Development Company storm monitor magnetometer was operated on the ground so that aeromagnetic data recorded during magnetic storms could be discarded. The data obtained during the Isurvey were compiled and interpreted in the Philadelphia, Pa., office of Aero Service Corporlation. Flying commenced on 1st April and was completed on 8th May, 1961. A total of 13,777 line-miles of traverses and tie lines was flown at a barometric altitude of 1500 feet above sea level. Traverses were oriented east-west at intervals of five miles, and tie lines were flown north-south across the survey area at intervals of twenty miles. The westernmost tie line was extended southwards from the southern boundary of the survey area for a distance of approximately 125 miles into the area of a previous reconnaissance survey carried out for Santos Limited. This survey consisted of approximately 2000 line-miles of traverse in the Lake Torrens area of South Australia. The traverses were arranged in a rectangular grid pattern consisting of five east-west lines at 35-mile intervals which were crossed by six north-south tie lines. The flight altitude was maintained at 1500 feet above sea level except in the south-central part of the area where it was increased to 4000 feet barometric elevation above sea level. A set of fourteen reconnaissance aeromagnetic traverses totalling 8721 line-miles had been flown previously by the Bureau of Mineral Resources across the Great Artesian Basin during 1958. Portions of several of these traverses cross the main survey area, but the majority are located in the peripheral areas. The flight altitude was maintained at 1500 feet above ground level.

Wandagee No. 1 Well was located in the Carnarvon Basin, Western Australia, approximately 84 miles north-east of Carnarvon. The well was drilled by Oil Drilling and Exploration CVV.A.) Fty Limited for West Australian Petroleum pty Limited, to a total depth of 3521 feet. Drilling commenced on 25th April, 1962 and was completed on 12th June, 1962. A full programme of logging, testing, and coring was undertaken. The well was sited on a shallow part of the Wandagee Ridge. After drilling through 26 feet of Quaternary sand, the well penetrated 556 feet of a normal Carvarvon Basin sequence of Cretaceous sediments. The Upper Devonian Gneudna Formation was encountered at 591 feet, and this was followed from 912 feet by a section ranging in age from Silurian to possible Ordovician. The well bottomed at 3521 feet in the Tumblagooda Sandstone after drilling through 861 feet of the formation. The primary objective of the well was to investigate the stratigraphy and oil potential of the Devonian and older rocks on a shallow part of the Wandagee Ridge. Traces of gas were observed in the marine siltstone unit at the top of the Tumblagooda Sandstone (2870 to 3098 feet), but no other hydrocarbon shows were recorded. Four drillstem tests recovered only brackish to salt water, The well was completed as a water well for Wandagee Station. The off-structure drilling operation at Wandagee No. 1 was subsidized under the Petroleum Search Subsidy Act 1959-1961, from surface to total depth.

A. F.O. lnderi No. 1 Well was located in the Bowen Basin, Queensland, approximately 15 1/2 miles north-west of Holleston. The well was drilled by Hichter Bawden Drilling Pty Ltd, under contract to Mines Administration Pty Limited, for Associated Freney Oil Fields N.L., to a total depth of 5433 feet. Drilling commenced on 29th June, 1963 and was completed on 11th .\ugust, 1963. A full programme of logging, testing, and coring was undertaken. The well was situated on or near the crest of the lnderi Anticline. Below a thin cover of Quaternary alluvium and Tertiary volcanic rocks the well penetrated Permian sediments from 92 feet to total depth. Economic basement was encountered at 5368 feet and the well was abandoned at 5433 feet in dominantly granite conglomerate. The Permian sediments included the Bandanna Formation, the Mantuan Productus Beds, "Dry Creek Shale", "Early Storms Sandstone", lngelara Formation, Aldebaran Sandstone, Cattle Creek Formation, and the Stanleigh Formation. The objective of the well was to test the hydrocarbon potential of the sediments in the lnderi Anticline, and to establish the section present in the area. Seismic evidence indicated a closure of 600 feet over an area of 15 square miles for the lnderi anticline itself, but closure is increased to 1000 feet over 45 square miles by upthrow against the Albinia Fault to the east. Eight open-hole formation tests were carried out. A gas flow of 800 Md/ D was recorded from the interval 1818 to 1901 feet (DST No. 4). Four of the tests yielded hydrocarbons. Three of these (DST' s Nos 1, 3, and 4) tested the same topmost sand of the Aldebaran Sandstone, and the fourth tested the inteval 3814 to 3944 feet (DST No. 7). Traces of cutting fluorescence were recorded from the Aldebaran Sandstone between 2140 and 2480 feet and live oil was found along a bedding plane in a fairly tight sandstone from Core No. 8 (2456 to 2466 feet). However, DST 1'0. 5, over the interval 23:32 to 2466 feet, produced fresh water only. No other flow was recorded and the well was plugged and abandoned. The stratigraphic drilling operation at A.FO. lnderi No. I was subsidized Under the Petroleum Search Subsidy Act 1959-1961, from surface to total depth.

Delhi-Santos Gidgealpa No. 1 Well was drilled in the north-eastern corner of South Australia by Delhi Australian Petroleum Ltd, as operator, and Santos Limited. The well is 60 miles south-west of Innamincka No. 1 and 50 miles west-north-west of Dullingari No. 1. Gidgealpa No. 1 was spudded on 28th August, 1963, reached a total depth of 13,114 feet on 27th November, 1963, and was completed as a water well flowing from the Mooga Sandstone on 6th December, 1963. A National 80-B rig, owned and operated by Drilling Contractors (Australia) Pty Ltd, was used to drill the well. Gidgealpa No. 1 was drilled as an off-structure well on the flank of a prominent closed anticline. The Mesozoic sequence was the thickest yet encountered in wells in the western part of the Great Artesian Basin, and very similar to that found in Innamincka No. 1. The overall lithology of the Permian in Gidgealpa No. 1 resembles that in Dullingari No. 1 although detailed correlation is not possible. Below the regional angular unconformity at the base of the Permian, a thick sequence of Cambrian marine carbonates and tuffaceous sediments was penetrated. This was the first encounter of Cambrian rocks in the subsurface of the Great Artesian Basin. More hydrocarbon shows were encountered in the Permian sequence in this well than in any other drilled to date in this region. Unfortunately the sandstones exhibited very low porosity. A deep zone of porous dolomite, some 400 feet thick, was also discovered in the Middle Cambrian, and on test, flowed very gassy saltwater. Thus Delhi-Santos Gidgealpa No. I, in addition to providing much new geological information, gave most encouraging indications that, under favourable conditions, the Permian and the newly discovered Middle Cambrian dolomite could produce hydrocarbons. The off-structure drilling operation at Delhi-Santos Gidgealpa No. 1 was subsidized under the Petroleum Search Subsidy Act 1959-1961, from surface to total depth.

Delhi-Santos Gidgealpa No. 2 Well was located in the Coopers Creek area in the far north-eastern corner of South Australia, two miles due west of Delhi-Santos Gidgealpa No. 1. The well was drilled by Drilling Contractors (Australia) Fty Ltd for Delhi Australian Petroleum Ltd and Santos Limited, to a total depth of 9020 feet. Drilling commenced on 12th December, 1963, and was completed on 10th February, 1964. A full programme of logging, testing, and coring was undertaken. Mter passing through 618 feet of Recent and Tertiary sediments, the well penetrated 2277 feet of Upper Cretaceous, 1970 feet of Lower Cretaceous, 1681 feet of Jurassic, 124 feet of Triassic, and 182 feet of Permian. Below the regional angular unconformity at the base of the Permian at 6868 feet, a thick series of early Palaeozoic or Proterozoic tuffs and trachytic lavas was drilled to total depth. This series was in marked contrast to the Cambrian sediments found below the Permian in Gidgealpa No. 1. Gidgealpa No. 2 was drilled primarily to test the Permian and Cambrian potential reservoir beds found in Gidgealpa No. I, in a favourable structural position. The No. 2 well was drilled high on the Gidgealpa structure, immediately after the completion of the No. 1 well which was located on the flank of the anticline. The formations encountered in Gidgealpa No. 2 down to the base of the Permian section, were found to be lithologically the same as in Gidgealpa No. I, but they are thinner, the Winton Formation, Lower Triassic, and Permian rocks markedly so. Thirteen drillstem tests were run over intervals between 6465 and 7595 feet. Five of these tests were run in open hole and the remainder through perforations in the 7" casing. Four of the tests yielded substantial quantities of gas, and the well was completed as a shut-in gas well capable of yielding 11.6 million cubic feet of gas and 42 barrels of condensate daily, through a half-inch choke at a pressure of 2015 psi., from four Permian sandstones with a combined thickness of 61 feet. The calculated absolute open flow potential of Gidgealpa No. 2 was 29.5 million cubic feet of gas per day. The test drilling operation at Delhi - Santos Gidgealpa No. 2 was subsidized under the Petroleum Search Subsidy Act 1959-1961, from surface to total depth.

Ooraminna No. 1 Well, located 42 miles south-east of Alice Springs on the Ooraminna Anticline, in the Amadeus Basin of the Northern Territory, was the first oil exploratory test drilled in the Amadeus Basin. The well was drilled by Oil Drilling and Exploration Limited for Exoil (N. T.) pty Ltd, to a total depth of 6107 feet. Drilling commenced on 24th February, 1963 am was completed on 5th June, 1963. A full programme of logging, coring, and testing was undertaken. The well spudded in the Cambrian Arumbera Sandstone and entered the Upper Proterozoic Pertatataka Formation at 1530 feet, the Areyonga Formation at 3734 feet, and the Bitter Springs Formation at 4406 feet. Drilling stopped at 6107 feet in evaporites of the Bitter Springs Formation. Four drillstem tests were run over intervals between 3761 and 3950 feet. The only successful test was DST. No. 4, over the interval 3761 to 3906 feet in the Areyonga Formation, when a flow of gas (84.2% methane) at a rate of 12,000 cubic feet per day was measured. Salt was foum in the Bitter Springs Formation, in the bottom 162 feet of the hole. The stratigraphic drilling operation at Ooraminna No. 1 was subsidized under the Petroleum Search Subsidy Act 1959-1961, from surface to total depth.