F55/B1-13 Vertical scale: 100

No abstract available

F55/B1-9 Vertical scale: 100

The Meda No. 1 Well was drilled with WAPET's National 100 rig to the total depth of 8,809 feet. The well was spudded in alluvium, which overlies the Blina Shale to 60 feet. Below the Blina Shale, the Permian sequence was penetrated, consisting of the Liveringa Formation, Noonkanbah Formation, Poole Sandstone with its Nura Nura Member, and Grant Formation. A disconformity is present between the Poole Sandstone and the Grant Formation. The Grant Formation unconformably overlies the Anderson Formation (Upper Carboniferous) at 4,201 feet. The Laurel Formation (Lower Carboniferous) was penetrated from 4,935 to 5,483 feet. The boundary between the Lower Carboniferous and Upper Devonian (5,483 feet) is tentatively picked at the change from interbedded limestone and siltstone to oolitic limestone. The main objective ofthe test, the Upper Devonian reef complex, was penetrated at 6,620 feet and drilled to the basal conglomerate at 8,360 feet. Precambrian basement was encountered at 8,663 feet. The Permian and Carboniferous sequences could be correlated with the equivalent sequences in The Sisters No. 1 Well. Because of different facies, no formation correlations could be made in the Devonian sequence. The test resulted in the recovery of several gallons of paraffin-base crude oil. The oil-bearing zone is in the upper part of the Laurel Formation and is confined to a bed of fine-grained slightly porous, calcareous and dolomitic sandstone between 5,125 and 5,133 feet. However because of slight permeability and high water saturation this zone is of no commercial value in this well. Numerous gas zones were penetrated in the Upper Devonian reef complex but they yielded only weak gas flows, predominantly of methane. The discovery of hydrocarbons in the Laurel Formation and Devonian reef complex makes Meda No. 1 of great importance in oil exploration of the Kimberley district. The drilling results show that future oil exploration on the Lennard Shelf should have two main objectives: (a) structural closures in the Lower Carboniferous (b) Devonian reef facies.

Frome Rocks No. 1 Well, which is situated on the northern edge of the Jurgurra Terrace, drilled to 734 feet through Recent sand and the normal sequence of Jurassic sediments of the South Canning Basin and then entered the top of the Frome Rocks Salt Dome. The Frome Rocks Salt Dome consists of l,522 feet of dolomite breccia cap rock and 1,747 feet plus of salt. The base of the salt was not reached. The age of the sediments composing the salt dome is not known, but slender evidence suggests that the age is Devonian to Lower Carboniferous. The intrusion of the salt dome probably took place in post-Permian and pre-Jurassic times. No signs of hydrocaroons were seen in the well and no formation tests were conducted. The Frome Rocks No. 2 Well drilled through 206 feet of Recent and Jurassic sandstones, and a standard Permiansequence (3,351 feet thick) to 3,557 feet. A thick sequence of uppermost Devonian (Middle to Upper Famennian) sedimentswas encountered between 3,557 feet and the total depth of 7,504 feet. This thick Devonian succession (3,947 plus feet) has been divided into two formations, one of siltstone and shale with some limestone and sandstone, from 3,557 feet to 6,264 feet, and the other of siltstone, from 6,264 feet to 7,504 plus feet. The primary objective, the Ordovician, was not reached. Persistent, though slight, hydrocarbon shows occurred in several zones throughout the upper two-thirds of the Devonian in the form of fluorescence associated With limestones, and a spotty oil staining in the uppermost sandstone bed. No hydrocarbons were detected by gas detection equipment. None of the hydrocarbon shows was of sufficient significance to warrant testing. In the Frome Rocks area, there is an association of a salt dome, a thick impermeable sequence, source rockpotential, and some reservoir potential. Should the same association occur in other areas along the Jurgurra Terrace, particularly if the reservoir potential improves, the petroleum prospects of the area must be upgraded.

A seismic reflection survey was conducted on behalf of L.H. Smart Oil Exploration Company Limited by Geosurveys of Australia Ltd during 1959. The survey consisted of a number of shot-points placed at one or two-mile intervals along lines across the Canaway anticline, the Pinkilla anticline, and the Chesson (Orient) anticline of the Grey Range. The purpose of the survey was to provide detailed information of the subsurface structure of anticlines indicated by surface geology. The survey was interpreted with reference to geology known from the Bulgroo bore on the western limb of the Canaway anticline. Seismic operations clearly indicated that surface fold structure continues and is enhanced with depth; the anticlines are caused by buried ridges, probably with Precambrian core-rocks. Permian to Cretaceous sediments are draped over these ridges and have a minimum thickness of about 4,000 it across the Canaway anticlinal crest; in the adjoining trough syncline, they thicken rapidly to 10,000 it or more.

A reflection seismic survey was conducted in 1959 on Authority to Prospect 55P by Austral Geo Prospectors Pty Ltd for Associated Australian Oilfields N.L. (A.A.O.), through A.A.O.'s management affiliate, Mines Administration Pty Ltd. The survey was made in the vicinity of the Arcadia Anticline, about 90 miles north of Roma, Queensland. Two exploratory bores had been drilled on the Arcadia Anticline, the first by Oil Search Ltd in 1936, and the second by Associated Australian Oilfields N.L. in 1957. The Oil Search test yielded a gasflow, mainly of carbon dioxide, of 3,000,000 cu.ft per day from the Staircase Sandstone. Shows of oil and gas encountered in the Associated Australian Oilfields bore were insignificant. The purposes of the seismic survey were as follows:- (1) To outline subsurface structural conditions; (2) To indicate whether a more detailed reflection seismic survey might locate drilling sites more favourable for the accumulation of oil or gas than those of the O.S.L. No.3 and A.A.O. No.7 Bores. The three horizons that were mapped showed a general conformity of structure but the maps showing the intervals between the mapping horizons indicated a lack of conformity in thickness of the strata. These results led to the conclusion that the Arcadia Anticline is a fold of recent geological age. The seismic data indicated that the Oil Search No. 3 Bore was drilled on the crest of the Arcadia Anticline. Additional seismic work would be necessary to determine the most favourable location for further investigation.

This report refers to a seismic reflection survey conducted near the town of Muttaburra in Queensland, between 16th October and 12th December, 1959, by Geoseismic (Australia) Ltd, for the Artesian Basin Oil Company Pty Ltd. The purpose of the survey was to determine the nature of any structures present and the thickness of the sedimentary rocks. A number of isolated reconnaissance lines were laid and the shot-points were placed at one or two mile intervals. The records were computed by jump correlation. One structural feature found as a result of the reconnaissance traverses was investigated by more detailed work. A northerly plunging anticline, with easterly dip contrary to the regional westerly dip was delineated on two reflecting horizons. The relief due to the easterly dip is approximately 250 feet on the deeper horizon and 200 feet on the shallower horizon. To investigate the area fully, it would be necessary to carry out a further seismic reflection survey using the continuous profiling method of recording and computing.

A reflection seismic survey was conducted in 1959-60, east of Roma, Queensland, on Authority to Prospect 55P, by Austral Geo Prospectors Pty Ltd for Associated Australian Oilfields N.L., through their management affiliate, Mines Administration Pty Ltd. The primary purpose ofthe survey was to locate positions most favourable for the accumulation of oil and gas. One well, Timbury Hills No. 2, was drilled on a structure indicated by this survey and produced 1,250,000 cubic feet of gas per day. A second well, Pickanjinnie No. 1, tested 6,500,000 cubic feet of gas per day. The seismic survey indicated several possible positions for future bore-holes, and there are indications of structures near the edge of the area. In order that these may be investigated fully, more extensive seismic work should be carried out.

A reflection seismic survey was conducted in late 1959 on Authority to Prospect 55P by Austral Geo Prospectors Pty Ltd for Associated Australian Oilfields N.L. (A.A.O.) through A.A.O. 's management affiliate, Mines Administration Pty Ltd, in an area south of Roma, Queensland. The primary purpose of the survey was to determine the subsurface conditions producing the gravity maximum mapped by the Bureau of Mineral Resources in 1947-1948. No structural features worth drilling were found by the survey, but significant information regarding the geology of the area was obtained. A summary of the conclusions, using data from both the East Roma area (A.A.O., in preparation) and the South Roma area, is given below. (a) The Cretaceous or Upper Jurassic strata thicken toward the south. (b) The Lower Triassic or Permian strata become thinner toward the south and, in spite of the thickening of the formations near the surface, basement should be encountered at depths equivalent to those of the central portion of the East Roma area.