The Betoota No. 1 well was drilled by Delhi Australian Petroleum Ltd, Frome-Broken Hill Company Pty Ltd, and Santos Limited, in far southwest Queensland to a total depth of 9,824 feet. Drilling was commenced on 22nd December 1959 and the well was completed on 18th April 1960 as a dry hole. The rig used was a National 130 owned by Delta Drilling Company. Delhi Australian Petroleum Ltd, as the operating company, supplied the supervisory, engineering, and geological personnel. A comprehensive programme to obtain all data relative to the hydrocarbon potential of the strata penetrated by the drill bit and stratigraphic information concerning the geological history of the area was diligently carried out. The operation also provided for a complete programme of electric and mud logging, testing and coring, carried out by the operating company and their contracted service companies. The Betoota No. 1 well established the presence of 5,757 feet of Mesozoic strata overlying 4,067 feet of sediments of probable Palaeozoic age at the site of the bore hole. Several showings of hydrocarbons were detected in sediments between 4,400 feet and 5,757 feet. Mter testing and examination of all evidence, they were considered to be noncommercial. From 3,450 feet to 5,757 feet some zones exhibiting very good porosity were encountered, but all were found to be water-bearing. Shales of both marine and brackishwater origin, regarded as suitable source rocks, occurred in the well between 1,350 feet and 3,245 feet and between 5,000 feet and 5,757 feet. The rest of the section penetrated was composed of sediments whose origin did not suggest conditions of accumulation likely to foster the generation of fluid hydrocarbons.

Thangoo No. lA well was drilled as a result of mechanical difficulties encountered at the drilled depth of 3 ,475 feet in Thangoo No. 1 well which were insurmountable and prevented further operations on this well. Total loss of circulation at 3,475 feet in Thangoo No. 1 well resulted in unexpected total collapse of the hole below the 10 3/4" casing in a section of friable sandstone and conglomerate (Grant Formation). In Thangoo No. lA well these formations were cased off. A lost circulation zone was tested for potential hydrocarbon production and found to contain water only. The well was drilled to 5,429 feet into basement rocks (programmed depth 4,500 feet). Excellent hole control was maintained to total depth by drilling below the 16" conductor shoe with high pH, low shear and waterloss, freshwater mud. The 1,366 feet of Mesozoic and 1,377 feet of Permian section in Thangoo No. lA closely resemble that of Thangoo No. 1. The Ordovician section is 2,318 feet thick, consisting of 695 feet of Goldwyer Formation (new name) and 1,623 feet of Thangoo Limestone (amended name). Basement, consisting of Precambrian phyllite , was encountered at 5,100 feet in Thangoo No. lA. Traces of oil were observed throughout the Ordovician section. Oil shows are confined predominantly to vuggy veins of coarse crystalline dolomite. A minor show was also observed in the sandstone of the basal unit of the Thangoo Limestone. A porous zone within the Thangoo Limestone, causing some lost circulation, appeared at about 3,670 feet in Thangoo No. lA. A formation test of this zone recovered only brackish water (11,999 ppm. total salts) with no signs of oil or gas. It is possible that the small shows of oil in the Thangoo Limestone are retained by the impervious Goldwyer Formation, as no shows were present in the Roebuck Bay and Dampier Downs wells, where porous Permian rocks directly overlie the Thangoo Limestone. The correlation of the sections of the Thangoo Limestone in all the exploratory wells on the Broome Platform indicates that the Thangoo No. lA well occupies a low structural position. Consequently the objectives of testing the structure in the Ordovician and Permian Grant Formation were not achieved. The chances of finding commercial oil accumulations in the Ordovician section of the South Canning Basin in the vicinity of Thangoo Nos. 1 and lA are very small at this time, because of the low source rock potential and flushing by meteoric waters of the Thangoo Limestone, the lack of porosity in the Goldwyer Formation, and the difficulties experienced in resolVing the structure of the Ordovician with present seismic methods.

The Barlee No. 1 Well was drilled with WAPET's National 100 rig to the total depth of 8101 feet. Below a thin cover of the surface sand, 1562 feet of Mesozoic sediments were encountered, and drilled to the depth of 1594 feet. These sediments are represented by the Broome Sandstone (Lower Cretaceous) and Jurassic rocks, consisting of Jarlemai Siltstone, Alexander Formation, and Wallal Sandstone. The Jarlemai Siltstone interval which is 850 feet thick, is the thickest section of this formation which has been drilled in the Canning Basin. Unconformably below Mesozoic sediments, a uniform section of Carboniferous rocks was encountered and drilled to the total depth. All 6507 feet of the Carboniferous section are included in the Anderson Formation, to which an Upper Carboniferous age is tentatively assigned. In the lower part of the formation (7825 - 7856 feet) an intrusive body of dolerite was encountered. Some induration was observed in rocks adjacent to the intrusion. The well was abandoned in moderately porous sandstone beds of the Anderson Formation. Average dips of 20 degrees were observed in cores and recorded by the dipmeter survey in the Carboniferous section. The dipmeter survey shows that the well was located on the northern flank of the Barlee Anticline. Some very slight shows of gas were present in the sandstone beds of the Anderson Formation. Below 5600 feet some sandstone beds contained impregnations of black, rubbery bituminous material - very probably oil residue. No signs of live oil were observed in the well. The drilling results indicate that the Barlee No. 1 Well (like Fraser River No. 1) is located in the deep Fitzroy Trough on a structure originated by an igneous intrusion. The prospective beds of Ordovician, Devonian, and Lower Carboniferous rocks are buried under the thick cover of the unprospective Upper Carboniferous sediments and probably are intruded by igneous rocks. It seems likely that the sediments of the Fitzroy Trough in the Barlee area extend south as far as the Darnpier Fault; thus the Dampier Fault in the western part of the Canning Basin may replace the Fenton Fault, which dies out before reaching the Dampier Land area. The concept of the Jurgurra Terrace still remains valid, but only for the eastern part as shown on Plate .No. 1.

This report refers to seismic work carried out in the Puri area of Papua by Seismograph Service Ltd. for Australasian Petroleum Co. Pty. Ltd. during the period 6th May - 15th December, 1959. The objective ofthe survey was to determine the structural pattern of the Tertiary limestones in order to define any closed structures that may have economic oil accumulations. Altogether some 75 miles of continuous reflection traverses were observed and also a single refraction in-line profile of two spreads. An anticlinal feature was observed along one line but as there was no evidence of any significant pitch reversal along the strike line it seems there is no structure worth drilling in the area south of the Puri and Kereru Anticlines. The overall quality of the reflection data was poor but was considered adequate to disprove the presence of any major closed structures.

This report covers gravity survey work conducted by Mines Administration Pty. Limited for Associated Freney Oil Fields N. L. during the period 20th June to 31st July 1959. The survey was conducted in conjunction with the seismic survey carried out by the Bureau of Mineral Resources. The purpose of the work was to define at depth the limits of the Cooroorah Anticline, Central Queensland. Gravity values were observed and plotted over the whole of the Cooroorah area, and, in particular, over the Cooroorah Anticline. These values indicate a broad gravity '''low'' south of the Mackenzie River and west of Bluff. This is confirmed by the previous regional gravity survey of 1958. Over the Big Churchyard Culmination of the Cooroorah Anticline the gravity gradient reverses. The axis of this reversal is displaced approximately 1 1/4 miles north-west from the axis of the Cooroorah Anticline. The seismic survey shows that the structure at depth is closely conformable with the surface structure so it appears from this displacement of gravity and geological axes that the gravity "high" is due to some deep-seated density variation.

This report covers gravity survey work conducted by Century Geophysical Corporation for Magellan Petroleum Corporation during the period 1st July to 31st December 1959. The survey was made following an aeromagnetic survey. The gravity survey was intended to corroborate the magnetic interpretation; to provide further information as regards depth to basement and fault systems; and to indicate structural "highs" which could then be more precisely delineated by seismic reflection methods. Gravity values were observed and plotted over the area surrounding Winton, Queensland. Both the gravity survey and the aeromagnetic survey indicate a fault or fault zone across the area. In an appendix by the Bureau of Mineral Resources, it is stated that a seismic profile crossing this zone indicates that this zone is either a fault or a monoclinal fold. Magellan Petroleum Corporation are planning to deepen the water bore at Corfield, and if this does not provide sufficient information regarding the deeper rocks, a further stratigraphic test will be drilled at Winton.

A number of selected specimens from the Tennant Creek mining field were submitted for examination by N.J. McMillan. The object was to investigate the possibility that the talc in the area was derived by the metamorphism of ultrabasic rocks.

This publication presents the scientific and technical results obtained from the drilling of a deep test well at Puri in Western Papua, by the Australasian Petroleum Company Pty Ltd. These results were originally submitted by the company in a completion report on the well, written in two parts: Part I, Geology, by C.E.P. Hull, which -includes a report on the palaeontological examination of samples from the well, by F .C. Dilley. Part II, Petroleum Engineering, by M.W. Clegg, including the information obtained from testing and the results of oil, gas anj water analyses. This information has been combined into one volume. The authors of the various chapters are indicated in the table of contents. The formal Papuan stratigraphic nomenclature is at present being studied by the geological staff and advisers of the Australasian Petroleum Company Pty Ltd in London. As this study is not complete, the stratigraphical names in common use by the operating company have not been submitted for the formal approval of the Australian Stratigraphical Nomenclature Committee. Accordingly, within this report Miocene stratigraphical units are designated by informal geographical stage names and an appropriate lithological term. The Eocene and Cretaceous sediments encountered in the well are not subdivided but are merely referred to a Eocene limestone and Cretaceous shale. Two deviated holes, Puri No lA andPuri No 1B, were drilled from Puri No 1, but as these were not subsidized under the Petroleum Search Subsidy Acts, information from these holes is not included in this report.

Samphire Marsh No. 1 Well was drilled to a total depth of 6664 feet as a stratigraphic and structural test in the South Canning Basin. The drill passed through 120 feet of Quaternary silt and limestone, 2124 feet of Mesozoic sandstone and siltstone, 1811 feet of Permian marine beds, partly of glacial origin, and 2541 feet of Lower Ordovician shale with sandstone at the base. The drill encountered Precambrian granite at 6610 feet, confirming the geophysical estimate of depth to basement. None of the sediments present in the well are considered likely to be a source for hydrocarbon accumulations. No signs of hydrocarbons were seen in this well.

During 1950-51 pendulum gravity observations were made at 59 stations throughout Australia using invar pendulums on loan from the Department of Geodesy at Cambridge University. A national gravity base station was established at Melbourne. Subsequent comparisons with gravity meter ties suggest that the pendulum value is about 2 mgal. low. The standard errors of the gravity differences from Melbourne to the other stations have been estimated from internal consistency of the pendulum observations and from comparison with gravity meter measurements; the mean standard error is about 0.6 mgal. A small systematic difference from gravity meter values is assumed to be caused by the effect of the earth's magnetic field on the pendulums; after correction for this, the results agree fairly well with the American calibration system. Free air, Bouguer and isostatic anomalies have been calculated for all stations. The isostatic anomalies are for both Airy-Heiskanen and Pratt-Hayford hypotheses, and for four different assumed crustal thicknesses in each case. The isostatic and Bouguer anomalies are predominantly negative. A degree of isostatic compensation is present, but some large anomalous areas are uncompensated. The pendulum survey forms a basic network to which past and future gravity surveys can be referred.