bluuebunny/crossref_metadata_2025 huggingface dataset:
GEOTECHNICAL ASPECTS OF FOUNDATION INVESTIGATIONS FOR PRODUCTION PLATFORMS AT NORTH RANKIN
Authors: King R.W.
Published: August 2017

Production platforms required for the development of the North Rankin gas/condensate field will be founded on deep deposits of loose to weakly cemented calcareous material of predominantly marine origin. Although the data base for foundation design in these materials is extremely limited, experience has shown that calcareous sediments exhibit unusual engineering characteristics and that in situ load tests appear to be the most reliable indicator of soil-bearing potential.The foundation investigations performed at North Rankin, in 1978, integrated conventional soil sampling techniques with cone penetrometer testing (CPT), which is a small-scale load test that provides a semicontinuous profile of soil resistance. This being the first time that CPT had been used extensively in calcareous sediments, a series of innovative prototype in situ load tests were performed to provide data for calibration of the core resistance profile.A modified carbonate classification system was introduced into the programme and, together with detailed geological analysis of specimens, it provided an insight into subtle variations in lithology and cementation throughout the profile.These new developments and the comprehensive nature of the investigation produced a large amount of data that are relevant to other locations where similar sediments exist.As a result of these investigations and subsequent studies, Woodside Petroleum Development has been able to progress confidently in the definition of a suitable foundation system and the design of the North Rankin platforms.
FOCUS ON CHINA : JURISDICTIONAL CLAIMS, CURRENT PETROLEUM DEVELOPMENT
Authors: Mukhtar K. , Morrison M.R.
Published: August 2017

China has made extensive claims to the offshore resources in the Yellow Sea, the East China Sea and the South China Sea. In the East China Sea, China claims sovereignty over the entire continental shelf. South Korea, Japan and Taiwan also claim seabed rights on the continental shelf. These claims overlap particularly in the prospective oil-bearing area west of the Okinawa Trough. The relevant principles of international law advanced by these countries in support of their respective claims are also examined. The disputes involve a complex mix of political, economic, legal, historical and cultural factors. In the South China Sea the disputes mainly concern the ownership of islands as distinct from competing claims to the continental shelf in the East China Sea. The most significant of these disputes is between China and Vietnam and particularly concerns the Parace and Spratly Islands.The People's Republic of China is determined to become a major world oil producer. The technology and huge finance required to achieve this objective must be obtained by co-operating with foreign sources. In order to co-ordinate this activity, the Chinese have established a complex petroleum administration. Examination of China's recent production history and ambitions demonstrates the need for China to seek foreign assistance to obtain production targets. China has recently concluded geophysical agreements with foreign entities in eight offshore areas. In addition, it has concluded an ambitious exploration/development agreement with Japan National Oil Corporation. The experience of industry in dealing with Chinese authorities with special emphasis on negotiating techniques is briefly described.
THE EYRE SUB-BASIN: RECENT EXPLORATION RESULTS
Authors: Bein J. , Taylor M. L.
Published: August 2017

The Eyre Sub-basin of the Great Australian Bight Basin comprises a series of half-grabens with a maximum sediment thickness in the order of 6 000 m. It is bounded to the north by high-standing basement with a sedimentary cover about 550 m thick. To the west, sedimentary cover gradually thins and onlaps rising basement. To the south, a high- standing basement ridge separates the sediments within the Eyre Sub-basin from those of the Great Australian Bight Basin proper. The sedimentary pile apparently thickens south of the basement ridge where water depth increases to more than 1 400 m.The high basement trend bounding the sub-basin to the south plunges gradually to the east where it is eventually broken up by faulting. Seismic data from the eastern end of the sub-basin show progressive down-faulting of basement and increasing sediment thickness to the south.Jerboa 1 was drilled on a tilted basement fault block. It penetrated 1 739 m of sedimentary section, which is believed to be a condensed sequence representative of most of the total sedimentary fill of the sub-basin. Middle to Late Jurassic (Callovian-Kimmeridgian) sediments were encountered above basement, and the sequence continued almost unbroken into the Late Cretaceous (Cenomanian). Minor unconformities occur between the non-marine Aptian sequence and the overlying marine Albian, and between the Albian and Cenomanian. A major unconformity separates the Cenomanian from the overlying Tertiary section, interpreted to have been deposited after the separation of Australia from Antarctica.
THE PETROLEUM POTENTIAL OF ANTARCTICA AND ITS CONTINENTAL MARGIN
Authors: Cameron P. J.
Published: August 2017

On the basis of geological comparison and analogy with other Gondwanaland continents, four regions of Antarctica and its continental margin offer potential petroleum-bearing basins.The area of the Weddell Sea, Byrd subglacial basin and Ross Sea is analogous to the area east of the Andes Mountains in Argentina and offers good petroleum potential.The divergent continental margin of East Antarctica is analogous to the southern Australian and East Brazilian margins and its continental shelf is likely to contain Late Mesozoic basins, perhaps with a variety of reservoir systems, having good petroleum potential.The wide continental shelves of the Bellinghausen and Amundsen seas on the West Antarctic margin may also present favourable areas of petroleum exploration. Large intracratonic basins in East Antarctica, although possibly geologically favourable for oil accumulation, lie beneath thick ice, are largely unknown, and are the least prospective of the four areas.The exploitation of any Antarctic mineral resources will require the resolution of sovereignty claims to Antarctica at present excluded from the Antarctic Treaty.
THE G-LOG* SEISMIC INVERSION PROCESS
Authors: Hays D. B. , Wardell J.
Published: August 2017

The G-LOG process is a method of seismic inversion which provides direct estimates of subsurface acoustic impedance from wavelet process stacked or migrated data. The fundamentals and characteristics of the inversion method will be discussed and examples of its use on Australian seismic data will be presented.G-LOG functions are derived by an iterative subsurface modelling technique based on a rigorous inversion of one- dimensional wave equation. This process finds the acoustic impedance model, or log, whose resulting wave-equation- consistent synthetic seismogram best matches the input seismic data in a least mean squared error sense. Multiple reflections are included in the synthetic seismogram, so that they become useful information in the determination of the log.Interval velocity logs are derived from the acoustic impedance logs. The results can be displayed in various forms, including detailed velocity logs, and colour-coded log 'sections' to match with the seismic section. Several examples of such results are presented.The G-LOG process is a revolutionary technique of subsurface modelling, and the logs it provides are strong indicators of subsurface lithology and will be an important tool in the evaluation and re-evaluation of potential hydrocarbon-bearing prospects.*Trademark of G.S.I.
ORGANIC PETROLOGY AND GEOCHEMISTRY OF SOURCE ROCKS IN THE PEDIRKA-SIMPSON BASINS CENTRAL AUSTRALIA
Authors: Smyth M. , Saxby J. D.
Published: August 2017

Sediments from the Permian Pedirka Basin and the overlying Triassic Simpson Desert Basin have been studied to determine their potentials as source rocks for hydrocarbons. Principal techniques used are reflected light microscopy, including vitrinite reflectance, solvent extraction and kerogen isolation.Dispersed organic matter (DOM) occurs through the Permian and Triassic sequences, and is most abundant near the top of the Triassic, constituting up to 2 per cent of the sediments by volume. Of this DOM, 30 to 50 per cent is vitrinite plus exinite. The Permian and Triassic coals have vitrinite reflectivities of up to 0.9 per cent. The geothermal gradient in the vicinity of Poolowanna 1 is probably sufficient to cause the cutinite within the Triassic sediments to break down into petroleum hydrocarbons. In the case of the Poolowanna Jurassic oil show, migration up faults and accumulation in high-temperature reservoirs have been accompanied by the loss of volatile hydrocarbons.
FIELD RESULTS USING MEASUREMENT-WHILE-DRILLING DIRECTIONAL SYSTEMS IN LONG BEACH, CALIFORNIA
Authors: Gearhart M.
Published: August 2017

One of the more extensive uses of directional drilling anywhere in the world has been in the development of the East Wilmington Oil Field in Long Beach, California. The average well is deviated from vertical in excess of 50° and wells with a maximum deviation in the 70° to 80° range are not uncommon before they are dropped off to 50° or less when penetrating the completion interval. Over 780 wells have been drilled in this field to date, requiring the highest degree of control and accuracy in order to avoid intersection of other wells and to obtain proper bottom hole spacing. The Measurement-While-Drilling (MWD) directional system has been tested on several wells and proven to provide the required accuracy, along with many advantages over past methods, used in the field development.Accurate transmission by MWD of bottom-hole measurements to the surface is provided by mud pressure pulses generated in the drill pipe downhole and detected by a pressure transducer includes the means for detecting, recording and processing these pressure pulses, to translate the information from the pressure pulses to rig floor displays usable by the drilling crew.
GEOLOGY, SOURCE ROCKS AND HYDROCARBON GENERATION IN THE CLARENCE-MORETON BASIN
Authors: Martin A. R. , Saxby J. D.
Published: August 2017

The geology and exploration history of the Triassic-Cretaceous Clarence-Moreton Basin are reviewed. Consideration of new geochemical data ('Rock-Eval', vitrinite reflectance, gas chromatography of extracts, organic carbon and elemental analysis of coals and kerogens) gives further insights into the hydrocarbon potential of the basin. Although organic-rich rocks are relatively abundant, most source rocks that have achieved the levels of maturation necessary for hydrocarbon generation are gas-prone. The exinite-rich oil-prone Walloon Coal Measures are in most parts relatively immature. Some restraints on migration pathways are evident and igneous and tectonic events may have disturbed potentially well-sealed traps. Further exploration is warranted, even though the basin appears gas-prone and the overall prospects for hydrocarbons are only fair. The most promising areas seem to be west of Toowoomba for oil and the Clarence Syncline for gas.
IMPROVED STRUCTURAL RESOLUTION FROM 3D SURVEYS IN AUSTRALIA
Authors: Sanders J. I. , Steel G.
Published: August 2017

Two marine seismic three-dimensional (3D) surveys were carried out in the Gippsland Basin during 1980. The results of these surveys illustrate the improved structural resolution that can be obtained by 3D migration in complex areas, and also the great detail with which a structure can be defined by the dense data volume given by a 3D survey.Certain aspects of data collection and processing are particularly critical in achieving a successful 3D survey. Line spacing and depth-point spacing must be related to the maximum dips and reflection frequencies expected, and accurate navigation and streamer positioning are essential. Correct migration of the data is highly dependent on obtaining the proper migration velocities, and these are derived from the stacking velocity analysis by a form of 3D modelling.Sections and Seiscrop' horizontal time slices from the surveys demonstrate that in areas of complex three-dimensional structures, 3D seismic methods are necessary to properly image the reflection energy. The Seiscrop sections also show how the dense spatial sampling of 3D data is required to map these complex structures with adequate resolution for the most effective planning of a drilling programme.
RECENT ADVANCES IN BURIAL AND THERMAL GEOHISTORY ANALYSIS
Authors: Falvey David A. , Deighton Ian
Published: August 2017

Geohistory analysis is a technique for plotting the cumulative subsidence of various chronostratigraphic horizons encountered in an exploration well or section. The intervals between horizons are corrected for sediment compaction and are plotted relative to an estimated ancient seabed (or land surface) as a function of geological time. Speed and precision have been added to this procedure by automatic computer processing and plotting. A variable eustatic sealevel datum has also been introduced. Accurate quantitative assessment of depth sub-seabed (or subsurface) of any horizon may be combined with a model of heatflow history for the well location to compute a maturation integral and theoretical vitrinite reflectance for that horizon as a function of geological time. Comparison of theory with present observations may be used to refine the model heatflow history. Palaeomaturation may be readily assessed.An offshore Perth Basin example is used to illustrate the effects of palaeosealevel, palaeoheatflow and unconformities and hiatuses. Analysis of a cross-section through three wells is used to demonstrate the potential for accurate calculation of a palinspastic section, palaeomaturation and migration direction. Geohistory analysis is demonstrated to be an essential tool in rigorous basin evaluation.
FINANCING RESOURCE DEVELOPMENT AFTER CAMPBELL
Authors: Gloster G. A.
Published: August 2017

The paper deals briefly with the basic nature of financial activity and markets and of the intermediaries, including banks, within these markets. It is argued that efforts by the authorities to affect monetary policy through controls on bank lending (quantitative and interest rates) are inefficient and only lead to circumvention. To the degree that prices (interest rates) are kept down in one area, they will be higher in another, and supply of credit reduced from one source will encourage a greater supply from another. The Campbell Committee's recommendations, if implemented, are likely to result in freer financial markets and to improve the resource development sector's access to finance. Clear examples would be the removal of foreign exchange restrictions and the setting up of a market-oriented exchange rate system. However, in one sense this access may be narrowed as the extension of bank-type prudential controls to bank subsidiaries and to all 'deposit-taking institutions' may impede the free functioning of financial markets as well as further entrenching the 'safeguarded deposit' concept over the community's savings.
GEOCHEMICAL CORRELATION OF AUSTRALIAN CRUDE OILS
Authors: Philp R. P. , Gilbert T. D. , Friedrich J.
Published: August 2017

Correlation of crude oils with either their suspected source rocks or other crude oils thought to be derived from similar sources is important for basin studies and their suspected source rocks or other crude oils thought to be derived from similar sources is important for basin studies and and source rock extracts using computerized gas chromatography — mass spectrometry (C-GC-MS). Biological markers are compounds that retain the structure of molecules occurring in living organisms during diagenesis and conversion of the original organic material to petroleum hydrocarbons. In general, the distribution of biological markers is identical for oils from similar sources and for their respective source rocks. Differences in sources or maturity of the oils lead to differences, sometimes very subtle, in the distribution of the biological markers.Results from C-GC-MS analyses performed on a series of oils from the Gippsland, Carnarvon and Surat Basins show how two classes of biological markers, namely steranes and triterpanes, can be used for correlation purposes. Oils from the Gippsland Basin can be divided into two groups differing in source and maturity. Similarly, the oils examined from the Dampier Sub-basin fall into two groups. It is proposed that they have at least one common source, with one group being distinguished by the presence of additional source material. Additional data are presented to show that the Barrow Jurassic and Windalia oils are derived from the same or similar sources and differ only as a result of the biodegradation of the Windalia oil. Results for the limited number of oils examined from the Surat Basin suggest the presence of at least two sources for the oils of this basin.
NEW AND FUTURE DEVELOPMENTS IN SEISMIC EXPLORATION
Authors: Savit Carl H.
Published: August 2017

Present research in reflection seismic prospecting is proceeding with three major goals.Intensive work is being done on the problem of obtaining useful reflections beneath complex near-surface materials. Such near-surface materials distort both the down-going and reflected wavefronts to an extent that deep reflections either cannot be distinguished or are so distorted as to conceal their true shapes. Current research seeks methods for obtaining enough information about near-surface irregularities to construct a model upon which to base a wavefront correction.The second major goal is to improve the resolution of the seismic reflection process. Resolution is lost because high frequencies are often weak in seismic sources and are severely attenuated by the earth, by receiver arrays, and by most processing steps. Seismic bandwidth can be increased by improving the high frequency output of the seismic source to compensate for attentuation in the earth, by reducing the size of receiver arrays, and by drastically reducing the inaccuracies of conventional processing algorithms.The third line of investigation seeks to increase the amount of information extracted from the seismic signal. The first step in this direction was the bright-spot technique, in which qualitative information on seismic reflection amplitudes was used to identify hydrocarbon deposits. Interval velocity estimation was a natural result of moving from a qualitative to a quantitative analysis of amplitudes. In theory, with a combination of P and S wave reflection data, virtually all elastic properties of subsurface rocks could be extracted from the data.In the more distant future, computers could handle complex interpretation tasks and make drilling decisions.The principal barrier to rapid implementation of virtually all of the new techniques is inadequate computer power. Despite the explosive growth of the power of computers, mainframe manufacturers have been unable to satisfy the even more rapidly increasing demands of geophysicists. Innovative processing techniques and specialized computer equipment will be essential to continuing rapid progress in geophysical exploration.
A PRECISE METHOD FOR DETERMINING CONTOURED SURFACES
Authors: Philip G. M. , Watson D. F.
Published: August 2017

Although the petroleum geologist is concerned with analysing three-dimensional data, he relies entirely on two-dimensional portrayals - cross-sections and particularly contour maps of all types. With the advent of digital computers, machine contouring has become increasingly common, but little attention has been directed to the limitations of the various algorithms that can be employed to generate contour maps from a set of control points. For example, it is not widely appreciated that contouring procedures which faithfully honour the value of original control points produce poor predictions at locations where no control is available. Contouring a published set of topographic data shows how this and other limitations lead to approximations and errors in machine-generated contours.A new method based on triangulation interpolation using Delaunay tessellations (deltri analysis) is superior to existing methods. Not only does the method give the most accurate and objective measurement and display of the contoured surface, but it is also computationally efficient. Rapid calculation of volume of closure over contoured structures is possible. The method also allows estimation of the adequacy of the data on which the contouring is based by introducing a measure of 'roughness' of the surface. This is achieved by analysing the directions of normals to triangles surrounding each control point.
FISSION TRACK ANALYSIS: A NEW TOOL FOR THE EVALUATION OF THERMAL HISTORIES AND HYDROCARBON POTENTIAL
Authors: Gleadow A. J. W. , Duddy I. R. , Lovering J. F.
Published: August 2017

Fission track dating is a new approach to the interpretation and quantitative modelling of thermal histories of sedimentary basins for hydrocarbon resource evaluation. This technique depends on the observation that annealing of fission tracks in minerals, like the generation and maturation of hydrocarbons, is a function of temperature and time. The temperature interval over which track annealing occurs in the mineral apatite, a common detrital mineral in sedimentary rocks, is virtually identical (60° to 125°C) with that required for the maximum generation of liquid hydrocarbons. Fission tracks in apatite separated from a rock sample thus contain a record of its heating in the oil generation window. The pattern of apatite fission track ages, together with detailed analyses of the distributions of track lengths, will yield information on thermal history unobtainable by other methods. The unique advantage of the fission track method is that it can give information not only on maximum palaeotemperatures, but also their variation through time.Fission tracks in detrital zircon and sphene are stable to higher temperatures (200° - 300°C) than in apatite enabling limits to be placed on maximum temperatures reached in sedimentary basins, as well as giving important information on sedimentary provenance.In the Otway and Gippsland Basins fission track ages and lengths determined on apatites, and ages determined on sphenes and zircons, have been used to reconstruct the thermal histories of different areas. Ages and track lengths of apatites from deep wells in the Otway Basin show the expected down hole decrease reaching zero apparent age where present well temperatures are about 125°C. The shape of the track length distribution is characteristic of the position of a sample within the track annealing zone and hence the oil generation window. Flaxmans-1 in the Otway Basin has an age profile indicating that present temperatures are at or very near the maximum experienced. In Eumeralla-1 sediments that lie above the present-day track annealing zone show clear evidence of track annealing in the past, indicating that temperatures have decreased. This is consistent with the relatively small amount of post-Early Cretaceous sedimentation observed in this well compared to Flaxmans-1.Fission track analysis thus has the potential of giving a new, quantitative perspective on the temperature history of rocks, which should have an important impact on techniques of petroleum exploration.
RECENT EXPLORATION AND PETROLEUM DISCOVERIES IN THE DENISON TROUGH, QUEENSLAND
Authors: Brown R. S. , Elliott L. G. , Mollah R. J.
Published: August 2017

Four gas fields (Glentulloch, Westgrove, Rolleston and Arcturus) were discovered by AAR Limited in the Denison Trough in the early 1960's. Permian gas reservoirs were encountered in Late Triassic wrench anticlines. The fields were not developed because of low gas prices and exploration technology problems at that time. Exploration activities ceased in 1970.Increased gas prices, the opportunity of an expanded gas market, and improved seismic technology provided the incentive to recommence regional seismic surveying of the basin in 1979. More than 2600 km of multi-fold seismic data have been recorded by the AAR Limited/Oil Company of Australia N.L. Joint Venture. The enhanced seismic resolution resulted in a revision of the structural and stratigraphic interpretation of the basin. Exploration drilling in 1981 was directed initially at deep Early Permian structures; however, reservoir quality of the Lower Permian sequence was poor and gas flow rates minimal.Exploration was therefore redirected towards the definition of prospects which were structurally and stratigraphically similar to the known fields. Five exploration wells have been drilled since November 1981, resulting in the discovery of a further three gas fields — Merivale, Yellowbank and Punchbowl Gully. Appraisal wells were drilled on the Glentulloch, Westgrove, Merivale and Yellowbank Fields, and were cased for future production.It is estimated that nine billion cubic metres (x 109m3) of conventional gas reserves are present within the basin. In addition, tight reservoirs contain large volumes of gas which may be producible by hydraulic fracturing. The basin is being actively explored to realize its full potential and to supply industrial and domestic markets in central and southeastern Queensland.
THE YELLOWTAIL OIL DISCOVERY
Authors: Limbert A. R. , Glenton P. N. , Volaric J.
Published: August 2017

The Esso/Hematite Yellowtall oil discovery is located about 80 km offshore in the Gippsland Basin. It is a small accumulation situated between the Mackerel and Kingfish oilfields. The oil is contained in Paleocene Latrobe Group sandstones, and sealed by the calcareous shales and siltstones of the Oligocene to Miocene Lakes Entrance Formation. Structural movement and erosion have combined to produce a low relief closure on the unconformity surface at the top of the Latrobe Group.The discovery well, Yellowtail-1, was the culmination of an exploration programme initiated during the early 1970's. The early work involved the recording and interpretation of conventional seismic data and resulted in the drilling of Opah- 1 in 1977. Opah-1 failed to intersect reservoir- quality sediments within the interpreted limits of closure although oil indications were encountered in a non-net interval immediately below the top of the Latrobe Group. In 1980 the South Mackerel 3D seismic survey was recorded. The interpretation of these 3D data in conjunction with the existing well control resulted in the drilling of Yellowtail-1 and subsequently led to the drilling of Yellowtail-2.In spite of the intensive exploration to which this small feature has been subjected, the potential for its development remains uncertain. Technical factors which affect the viability of a Yellowtail development are:The low relief of the closure makes the reservoir volume highly sensitive to depth conversion of the seismic data.The complicated velocity field makes precise depth conversion difficult.The thin oil column reduces oil recovery efficiency.The detailed pattern of erosion at the top of the Latrobe Group may be beyond the resolution capability of 3D seismic data.The 3D seismic data may not be capable of defining the distribution of the non-net intervals within the trap.The large anticlinal closures and topographic highs in the Gippsland Basin have been drilled, and the prospects that remain are generally small or high risk. Such exploration demands higher technology in the exploration stage and more wells to define the discoveries, and has no guarantee of success. The Yellowtail discovery is an illustration of one such prospect that the Esso/Hematite joint venture is evaluating.
SEISMIC INVESTIGATION OF THE MERRIMELIA FIELD
Authors: Smith B. L.
Published: August 2017

The Merrimelia oil and gas field, 40 km north of Moomba in SA, is located on the central dome of the Gidgealpa-Merrimelia-Innamincka Trend within the Cooper/Eromanga Basins.Geophysical studies have been instrumental in the investigation of the field since the discovery of commercial Permo-Triassic gas at Merrimelia- 5 in 1970 based on the results of the Merrimelia Seismic Survey. Subsequent seismic recorded during the 1980 Karawinnie Survey resulted in the location of Merrimelia-6 which, in 1981, discovered commercial oil in the Jurassic Namur Member and Hutton Sandstone, and Triassic gas, previously unknown.To allow accurate mapping of the field's oil reserves, a detailed half kilometre grid was recorded during the 1981 Namooka Seismic Survey. The programme comprised 110 km of 24-fold Vibro- seis coverage. Interpretation of the seismic and well data has resulted in recognition of a complex stratigraphic component superimposed on the Merrimelia structural high. Considerable detailed seismic work has contributed to a better understanding of the seismic reflection sequence and hence improved geophysical prognoses.Seismic studies of the Merrimelia field are continuing as further discoveries, most recently oil in the Triassic at Merrimelia-12 and gas in the Tirrawarra Sandstone at Merrimelia-13, are made in the field area.
A REVIEW OF THE RECENT EXPLORATION AND HYDROCARBON POTENTIAL OF THE AMADEUS BASIN, NORTHERN TERRITORY
Authors: Schroder R. J. , Gorter J. D.
Published: August 2017

Since commencing operatorship in the Amadeus Basin in June 1980, the Amadeus Joint Venture has acquired 3000 km of multifold seismic data and reprocessed 2500 km of existing single fold and multifold data. These data, integrated with geological, Landsat, gravity and airphoto information, led to the drilling of eight exploration wells, which resulted in two gas discoveries (in the Dingo 1 and West Walker 1 wells) and numerous additional oil and gas shows in the remaining wells.Interpretation of these multi-discipline data has enabled a number of significant structural trends and styles in the Amadeus Basin to be defined. Individual prospects within some of the major structural trends have now been tested by the drill. This paper describes the nature of these structural trends and illustrates geologically and geophysically typical examples of drilled prospects existing within these trends.The primary exploration targets in the Amadeus Basin are the Ordovician Stairway and Pacoota Sandstones (confirmed by the Mereenie Oil and Gas Field, Palm Valley Gas Field, and the West Walker gas discoveries) and the Precambrian-basal Cambrian Arumbera Sandstone (confirmed by the Dingo gas discovery). Geochemical and maturation data indicate that significant additional oil and gas accumulations can be discovered in these formations.Data from Dingo 1, Mt Winter 1 and Finke 1 have again indicated that significant quantities of both oil and gas have been generated in the Late Proterozoic sediments of the Basin. An active exploration program is continuing and will endeavour to confirm these expectations.
SOURCE POTENTIAL OF THE HORN VALLEY SILTSTONE, AMADEUS BASIN
Authors: Gorter John D.
Published: August 2017

The quantity of organic matter in the source beds within the Horn Valley Siltstone, as defined by the Total Organic Carbon content, increases westward from low values in the south and east of the Basin to maximum values in the Mt Winter and Mereenie areas. This westerly enrichment trend is paralleled by an improvement in source rock quality, as defined by the Hydrogen Index and Tmax crossplot of samples analysed by Rock-Eval pyrolysis.Earlier attempts to measure thermal maturation levels of source rocks in the Basin relied on the reflectivity of coalified graptolites but this method was only applicable to unweathered material obtained from the few and scattered bore holes in the Basin. In this study, conodont colour alteration is used to define organic maturation levels. This technique, newly applied in Australia, was used principally on samples collected from the Horn Valley Siltstone and has the practical advantage of being applicable to samples from both outcrop and subsurface localities.The study indicates that the conodont colour alteration isograds in the Amadeus Basin are primarily related to events of the Alice Springs Orogeny, when the thick mass of molasse sediments (Pertnjara Group) resulting from erosion of the uplifted Arunta Block was deposited. Anomalies in the conodont colour isograds are closely related to timing of structural growth during the orogeny and also possibly to the growth of salt structures.In addition, the study shows that burial at depths below 1500 m will have led to the catagenetic breakdown of reservoired oil and the production of only gaseous hydrocarbons from source beds.In combination, these two factors lead to the conclusion that the most prospective area for oil sourced by the Horn Valley Siltstone is north and west of the Mereenie Oil Field in areas of shallow burial.
GIFFSLAND HYDROCARBONS - A PERSPECTIVE FROM THE BASIN EDGE
Authors: Stainforth J. G.
Published: August 2017

Permit VIC/P19 lies palaeogeographically seaward of the main producing part of the Gippsland Basin. Deposition of the Latrobe Group commenced with volcanics and continental 'rift-stage' sediments during the Late Cretaceous. This phase was succeeded first by paludal sedimentation in the failed rift during the Campanian and Maastrichtian, and then by cyclic paralic sedimentation during the Paleocene and Eocene.Analysis of the hydrocarbons recovered during recent exploration of permit VIC/P19 shows that they were sourced from moderately mature coals and carbonaceous shales in the Campanian/-Maastrichtian paludal sequence.A maturation model that assumes elevated but decreasing heat flow, related to sea-floor spreading, produces an excellent fit to the observed maturity data and predicts a long history of hydrocarbon generation during the Tertiary. The maturity of the Upper Cretaceous source sequence depends more on the thickness of the overlying Lower Tertiary clastic Latrobe sediments than on the thickness of the Upper Tertiary carbonate wedge. The Late Tertiary phase of burial had relatively little effect on maturation because of its rapidity and the lower heat flow and higher thermal conductivities of the deeper sequence at the time. Overpressures in mature Upper Cretaceous source rocks, resulting from hydrocarbon generation, have driven pore fluids, including hydrocarbons, laterally up-dip into normally pressured reservoirs.The main oil province of the Gippsland Basin has a greater thickness of Lower Tertiary than has VIC/P19. As a result, source rocks are more mature there, and became wholly so by the end of deposition of the Latrobe Group. This facilitated charge of traps at the top of the Latrobe Group, which contain most of the oil and gas discovered to date in the Basin.
BASS AND GIPPSLAND BASINS: A COMPARISON
Authors: Davidson J. K. , Blackburn G. J. , Morrison K. C.
Published: August 2017

After two decades of exploration, one wireline test of oil, one of light oil and several of gas and gas/condensate have been recovered from the Bass Basin while the adjacent Gippsland Basin has established an estimated ultimate recoverable reserve of the order of half a billion kilolitres of liquids and a quarter of a trillion cubic metres of gas. Geologically, the basins are similar.The alluvial and nearshore deposits at the top of the Latrobe Group in Gippsland are as porous and permeable as similar deposits at the top of the Eastern View Group in Bass.The Eastern View and Latrobe Formations are regionally sealed by the Upper Eocene Demons Bluff and Oligocene Lakes Entrance Formations respectively. The intra-Latrobe section in Gippsland has significant but regionally not very extensive sealing units, whereas the Lower Eocene to Paleocene sequence in Bass is increasingly shale prone with depth, sometimes over-pressured, and constitutes an extensive seal for a base of Tertiary play. This play comprises Paleocene shales sealing Upper Cretaceous clastics with hydrocarbons potentially sourced from both units.Maturation studies (Saxby, 1980) indicate that the Upper Cretaceous is the principal source for hydrocarbons in Gippsland with possible lesser contributions from the Lower Paleocene and Lower Cretaceous. Limited data indicate the same is true in Bass and that the Paleocene and parts of the Lower Eocene are mature sources for gas/condensate and light oil. Normal faults assist vertical migration in Gippsland. In Bass, relatively few normal faults penetrate the Paleocene and Lower Eocene shales to reach the top of the Eastern View, greatly restricting the chances of vertical migration over much of the basin. Vertical migration is more likely beyond the margins of the depocentre.Eroded anticlines at the top of the Latrobe form large traps for the bulk of Gippsland's hydrocarbons. Small anticlines, wrench-related features and intra-Latrobe closures are more difficult to find. The normal fault blocks in Bass at the top of the Eastern View are wrench-modified and have proven difficult to define.The recent recognition in Bass of the base of Tertiary play and the need for careful structural and seismic interpretations is expected to lead to discoveries of oil and gas.
THE UNIONS — PARTNERS IN EXPLORATION?
Authors: Scoble J. P.
Published: August 2017

Industrial relations has been a 'sleeping giant' in the petroleum drilling industry in Australia. This is changing. Spurred on by successful militancy in Bass Strait and a growing awareness of the strategic significance of oil and gas to Australia's balance of payments, the unions are becoming more active in the drilling industry.The Northwest Shelf is representative of the oil and gas development projects which should provide long-term stability for the industry. The extent of their contribution to stability will depend on many factors, not the least of which is the industrial relations climate within which the developments take place. Unity among employers will be essential if important issues such as comparative wage justice, compulsory unionism and safety are to be successfully addressed. There is an urgent need for improved industrial relations planning at industry level.At the forefront of free enterprise, the petroleum drilling industry has discouraged the involvement of unions at every opportunity. This approach, appropriate in many parts of the world, may no longer be viable in Australia. A majority of Labor Governments, whose policies are strongly influenced by trade union attitudes, will provide a political climate conducive to an expanded union profile in the industry. It is time for the industry to re-examine the role of the union movement in its project developments and to accept the unions as necessary and interested participants in the development of Australia's resources.
PCD BITS IN THE OUTBACK
Authors: Barmby R. P. , Haines R. A.
Published: August 2017

SANTOS Ltd, as drilling operator in the Cooper Basin of South Australia, has experimented with polycrystalline diamond (PCD) drilling bits in a variety of medium-cost drilling programs. PCD bits were originally designed for use in high rotary speed, low weight on bit, shale drilling environments. The operator has succeeded in reducing drilling costs by 32 per cent in some low rotary speed, high weight on bit, sandstone drilling sections. This was achieved without significant alterations to the existing drilling program.The test runs of PCD bits also established optimum lithologies, optimum drilling parameters and techniques for detecting bit failure for use in the Cooper Basin. Drilling fluid systems and wellbore deviation control techniques were not altered while utilizing PCD drilling bits.SANTOS has also concluded preliminary testing of PCD core bits, and believes their economic application will expand in the future.
BARROW ISLAND CATHODIC PROTECTION SYSTEM — DESIGN, INSTALLATION AND COMMISSIONING
Authors: Lees A. J.
Published: August 2017

The Barrow Island oil field, with an area of about one hundred square kilometres containing over six hundred wells, presents an engineering challenge of vast magnitude in the protection of investment in the wells and their casings against the destructive process of corrosion. The growing incidence of casings leaks and escalation in the costs of repairing externally corroded casings provided the impetus for pilot scheme studies and subsequent design and installation of an impressed current cathodic protection system on a scale not previously undertaken in Australia.Data obtained from pilot scheme tests carried out in the latter half of 1979 established the basis of a feasible design. Detailed design and installation through 1980-81 was followed by commissioning of the first area of the system early in 1982.Design of the cathodic protection system was tailored to the local field conditions; the design was modified when necessary as installation and commissioning difficulties arose. Several minor operational problems encountered to date are still to be resolved.The total initial outlay of $5.7 million should result in minimum cumulative savings in well casing repair costs of $15 million over the next 15 years.
MASSIVE HYDRAULIC FRACTURE STIMULATION OF EARLY PERMIAN GAS RESERVOIRS, BIG LAKE FIELD, COOPER BASIN
Authors: Stanley D. J. , Halliday G.
Published: August 2017

In 1981, South Australian Oil and Gas Corporation Pty Ltd commenced a project to apply Massive Hydraulic Fracture (MHF) technology to the tight gas reservoirs of the Tirrawarra and Patchawarra Formations of the Big Lake Field. Four wells had defined the potential at depths of 8500-10 000 ft (2500-3000 m) in the early 1970s but early attempts to stimulate gas production were unsuccessful.The Tirrawarra Sandstone, as a massive unit of 120-200 ft (35-60 m) thickness, was a prime candidate. The Patchawarra sandstones, ranging up to 40 ft (12 m) thick and interbedded with shales and coals, presented a more difficult problem.Petrologic analysis disclosed quartz sandstones in which the pore system consists mainly of large irregularly shaped dissolution pores. Diagenesis has destroyed primary porosity and precipitated authigenic illite, illite-smectite, kaolinite and siderite. The gas contains 32 per cent CO2 and is very dry. Temperatures are close to 400°F (200°C). The formations are overpressured.The project has drilled two wells, Big Lake 26 and 27, and applied two MHF treatments in Big Lake 26. One further MHF remains to be done in Big Lake 27. Each MHF treatment has been tailored to the particular petrologic, reservoir, stratigraphic, pressure and temperature conditions of that zone. The tailoring of MHF design has been further refined by running a 'mini-frac' with 10 000 gal (45 000 L) of fluid. MHF designs have involved up to 620 000 lb (280 000 kg) of sand, 60 000 lb (27 000 kg) of sintered bauxite and 300 000 gal (1350 kL) of gel. Having management on-site to react to aberrations and vary the design has been important in operations.One Tlrrawarra Sandstone MHF has been unsuccessful (as predicted) and the other, on initial results, appears highly successful. The Patchawarra Formation MHF speared off into a coal but appears moderately successful. Long-term flow tests will provide definitive results.Encouraged by these initial results, the Joint Venture Partners have drilled two further wells in the Big Lake Field which await MHF treatment. The gas-in-place is estimated at about 1.5 trillion cubic feet (42.5 billion cubic metres). Three other tight gas prospects of similar size, Burley, McLeod and Kirby, have been identified. The size of this potential resource provides a strong incentive to attempt to make MHF treatments economically viable in the Cooper Basin.
DETERMINATION OF THE HYDROCARBON PROSPECTIVITY OF SEDIMENTS BY HYDROGENATION
Authors: Evans E. J. , Batts B. D.
Published: August 2017

Recent developments in hydrogenation procedures allow the liquid hydrocarbon potential and the total liquid hydrocarbon content of source rocks to be determined directly. In essence, mild controlled hydrogenation. without the cleavage of C-C bonds, converts the recognized hydrocarbon precursors in immature source rocks, i.e. the largely aliphatic acids, alcohols, esters, etc., into the parent alkanes. These alkanes, which have a distinctive composition, are easily collected and determined in toto by routine analytical processes. Thus hydrocarbon potentials are immediately revealed.Since the bulk of Australian crudes are of land plant (humic) origin, initial investigations have been largely concentrated on vitrinites and inertinites separated from Australian coals. These studies have shown that:the formation, on hydrogenation, of alkanes with a distinctive composition is an excellent guide to sediment maturity and to hydrocarbon potential; hydrocarbon generation, although not hydrocarbon maturation, is complete when the reflectance of vitrinite in contributing sediments approximates 0.65 per cent; and no significant difference exists between the hydrocarbon potentials and the hydrocarbon content of associated inertinites and vitrinites when the reflectance of the latter is in the range 0.3 to 1.2 per cent. These findings provide a guide to basin potentials and an explanation for the unexpected prospectivity of inertinite-rich Australian sediments.Results of applying this procedure to sediment samples from exploratory wells in the Gippsland and Cooper Basins have generally followed trends seen with coal samples and confirmed the value of the method in determining hydrocarbon potentials.
BIRKHEAD REVISITED: FETROLOGICAL AND GEOCHEMICAL STUDIES OF THE BIRKHEAD FORMATION, EROMANGA BASIN
Authors: Cook Michelle Smyth A. C. , Philp R. P.
Published: August 2017

Significant discoveries of oil have been made in Middle Jurassic sandstone reservoirs of the Birkhead Formation, Eromanga Basin, Australia.Some, or all, of this oil has been generated within the Birkhead Formation. A large proportion of the oil appears to be in relatively subtle traps. The source rock characteristics of the Birkhead Formation have been rated as fair to very good. In an attempt to improve the success rate in searching for less obvious reservoirs, a rating system based on the factors that control the location of hydrocarbon source rocks has been applied to many wells within the Birkhead Formation. The variables measured, which relate to source potential and maturation, were (1) thickness of shale units; (2) volume and type of dispersed organic matter; (3) volume and type of coal occurrences; and (4) rank.High values of source potential as measured by this rating system occur in the Birkhead Formation overlying the southwestern and northeastern parts of the Nappamerri Trough of the Cooper Basin. These areas include, or are close to, the known discoveries within the Birkhead Formation.In addition, investigation of the nature of the hydrocarbons produced from the Birkhead Formation using pyrolysis-gas chromatography (Py-GC) of whole rock samples and GC analysis of solvent extracts from the rocks indicates a terrestrial origin for the organic matter in most cases. Waxy oils could be expected from these samples under appropriate maturation conditions.