bluuebunny/crossref_metadata_2025 huggingface dataset:
MARINE MONITORING: CHRONIC OR ACUTE PROBLEMS
Authors: Farrell Peter , Yeates John
Published: August 2017

A mosaic-like compendium of information on the marine biotic environment of the North West Shelf has been compiled from a number of different sources. The areas most valued coincide with those most vulnerable to disturbance. Regulatory authorities require some form of impact assessment to be carried out by oil and gas explorers and producers as a condition of operation. Considerable expenditure is incurred annually by these companies in complying with these requirements, but current assessment methods do not always consider the scale of possible impacts nor the scientific validity of the results. Despite acceptance, and therefore implied approval of these assessments by the regulatory authorities, adjustments should be made to the current methodology to improve the cost effectiveness of the assessments and to improve the scientific validity of the results.Design of environmental impact assessment of exploration and production operations should consider the relative weighting given to potential acute versus chronic impacts. Prediction of possible impacts enables quantifiable relevant parameters for impact assessment to be identified. Monitoring of indicator species is a cost-effective method of detecting acute effects. Community census methods can be used to detect chronic effects.Statistical analysis of data is a vital, yet frequently ignored, aspect of environmental impact assessment, as is the depositing of voucher specimens for future reference. Statistical analysis can be based on either changes in the difference between specific parameters at the impact and control sites, or comparison of variance between sites over time. Decisions regarding sample area and number of sample replicates should be made based on the required precision of the assessment.
THE ENVIRONMENTAL MONITORING OF NATURAL EVENTS AND INDUSTRY ACTIVITY IN MERMAID SOUND, DAMPIER ARCHIPELAGO
Authors: Stejskal Iva V.
Published: August 2017

Various events, both natural and man-induced, have been identified as potential sources of disturbance to corals adjacent to the North West Shelf Project's Onshore Gas Treatment Plant on the Burrup Peninsula in the Dampier Archipelago. These events include cyclones, dredging and dredge spoil dumping operations, shipping activities, effluent discharge and oil spills.Environmental monitoring has indicated that the coral assemblages near the Onshore Gas Treatment Plant have been adversely affected by Project-related operations and tropical cyclones. The effects on corals due to dredging and spoil dumping activities have been shown to be localised and limited to a distance of 1.5 km from the nearest point of operation.Cyclone Ilona (1988) and Cyclone Orson (1989) were amongst the strongest recorded in the Dampier Archipelago. These cyclones caused extensive coral damage throughout the Archipelago, especially on the eastern side of Mermaid Sound. By 1990, recruitment of corals was observed at many of the sites indicating that corals were beginning to recover.
CALCITE-CEMENTED ZONES IN THE EROMANGA BASIN: CLUES TO PETROLEUM MIGRATION AND ENTRAPMENT?
Authors: Schulz-Rojahn J. P.
Published: August 2017

The occurrence of calcite cementation zones in oil- bearing sequences of the Jurassic-Cretaceous Eromanga Basin is of importance to petroleum exploration. The erratic distribution and thickness of these calcite-cemented intervals is problematic for both prediction of subsurface reservoir quality and structural interpretation of seismic data due to velocity anomalies.Carbon isotope signatures suggest the carbonate cements may form by dissipation of carbon dioxide upward from the Cooper Basin into the calcium-bearing J-aquifers of the Great Artesian Basin of which the Eromanga Basin forms a part. The model is feasible if the pH of the Eromanga Basin aquifer waters is buffered externally, by generation of organic acid anions during kerogen maturation or aluminosilicate reactions.Hydrocarbons are likely to have migrated up-dip along the same conduits as the carbon dioxide. Consequently, delineation of massive calcite-cemented zones in the Eromanga Basin reservoirs using well log and seismic data may aid in the identification of petroleum migration pathways, and sites of hydrocarbon entrapment.
THE STRUCTURAL AND STRATIGRAPHIC FRAMEWORK OF THE BEAGLE SUB-BASIN, IMPLICATIONS FOR HYDROCARBON MIGRATION AND TRAP DEVELOPMENT
Authors: Blevin J.E. , Stephenson A.E. , West. B.G.
Published: August 2017

The Beagle Sub-basin is situated in the northernmost Carnarvon Basin, northeast of Dampier, West Australia. Twenty years of exploration in the sub-basin has yielded disappointing results, and despite the drilling of ten wells, the area is considered an under-explored region of the Northern Carnarvon Basin. A regional study of open-file geophysical and geological data from the Beagle Sub-basin was undertaken in anticipation of gazettal of the area in late 1992.Regional mapping of structural elements in the basin included:a complex, E/W to NE/SW-trending basin margin fault system;N/S-trending intra-basin horsts (Sable, Ronsard and Picard Blocks);an E/W to NE/SW-trending trough system (Cossigny and Beagle Troughs); and,Outer Basin PlatformFive unconformity-bounded megasequences of Triassic to Cretaceous age were identified and evaluated with regard to depositional setting, reservoir, source and seal potential. Palaeogeographic maps were produced for four time intervals and relate basin development and stratigraphy to regional eustatic cycles.Traps in the basin were largely developed during the Triassic to Middle Jurassic period of rifting, and range from pre-breakup fault blocks to post-breakup sands that developed along the margins of emergent structural highs. Potential source intervals range in age from Early Triassic (Locker Shale) to Late Jurassic. Migration and entrapment of hydrocarbons from the principal source areas (the Cossigny and Beagle Troughs) is largely dependent on effective pathways and the presence of a regional Aptian age seal. Extensive wrench reactivation in the Miocene has occurred along the basin margin fault system, and may breach existing traps as well as create new plays.
THERMAL MODELLING IN THE EASTERN OTWAY BASIN
Authors: Cooper G.T. , Hill K.C. , Wlasenko M.
Published: August 2017

Vitrinite reflectance data across the Otway Ranges yield a thermal maturity map that indicates the presence of a broad NE-SW trending anticline with strong vergence to the southeast. Surface Rv max values for the central part of the ranges are >1.5 whilst those on both limbs decrease to Apatite fission track analysis of seven Eumeralla (Lower Cretaceous) samples from the coast around Wye River yields an AFTA age of 90±5 Ma, consistent with similar cooling ages measured around most of the SE Australia margin. Modelling of the data is consistent with a stratigraphic age of -100 Ma, rapid heating to −80°C for −5 Ma followed by cooling from 95–80 Ma and further cooling in the Miocene.Geologically the very large asymmetric anticline can be explained by inversion of a thick rift sequence along a major, listric northwest-dipping fault, perhaps soling at mid-crustal levels. This is consistent with structures observed offshore in the Torquay Embayment and is being tested by the AGSO deep seismic profile BMR 920T1. Observed gravity highs in the Otway Ranges may be associated with inverted high density sediments. Fission track analysis indicates that the major cooling was at −90 Ma, which is therefore likely to be the time of inversion. However, this implies compression during continental breakup, the mechanisms of which are not fully understood.
POST-CARBONIFEROUS TECTONIC EVOLUTION OF EASTERN AUSTRALIA
Authors: Elliott L.G.
Published: August 2017

Analysis of seismic data from the Bowen and Surat Basins has yielded valuable information on the Permian and Triassic evolution of eastern Australia. When combined with seismic data from the Clarence-Moreton and Maryborough Basins, a new understanding of the post-Triassic evolution of the region can be gained, with widespread implications for other eastern Australian basins.The Early Permian-Middle Triassic Bowen-Sydney Basin is a foreland basin system extending 2000 km in preserved section from Nowra in the south to Collinsville in the north. Permian outcrops as far north as Cape York were probably part of the same system prior to deformation and erosion. The basins in the Bowen-Sydney system were linked by similar structural and stratigraphic patterns controlled by a magmatic arc to the east. The Esk Trough and associated remnant basins east of the Taroom Trough were part of the Middle Triassic foreland sequence. The structural style in the system is dominated by thrusting from the east. An Early Triassic deformation is shown to be the most important, rather than the previously believed Middle Triassic event.The overlying Jurassic-Cretaceous foreland system, which included the Surat, Maryborough and Clarence-Moreton Basins, were once joined behind another magmatic arc, east of the Triassic arc position. A major mid-Cretaceous deformation is documented which fragmented the Jurassic-Cretaceous foreland basin into a number of remnant basins prior to the opening of the Tasman Sea in the Cenomanian. The dominant structural style is again thrusting from the east. Given the severity of the deformation, its effects are expected to be present in continental margin basins around Australia.
THE MOUNT ISA BASIN—DEFINITION, STRUCTURE AND PETROLEUM GEOLOGY
Authors: McConachie B.A. , Barlow M.G. , Dunster J.N. , Meaney R.A. , Schaap A.O.
Published: August 2017

The Mount Isa Basin is a new concept to describe the area of Palaeo- to Mesoproterozoic rocks south of the Murphy Inlier (not the Murphy Tectonic Ridge) and inappropriately described as the Mount Isa Inlier. The new basin concept presented in this paper allows the characterisation of basin-wide structural deformation and the recognition of areas with petroleum exploration potential.The northern depositional margin of the Mount Isa Basin is the metamorphic, intrusive and volcanic complex referred to as the Murphy Inlier. The eastern, southern and western boundaries of the basin are obscured by younger basins (Carpentaria, Eromanga and Georgina Basins). The Murphy Inlier rocks comprise the seismic basement to the Mount Isa Basin sequence. Evidence for the continuity of the Mount Isa Basin with the McArthur Basin to the northwest and the Willyama Block (Basin) at Broken Hill to the south is presented. These areas combined with several other areas of similar age are believed to have comprised the Carpentarian Superbasin.The application of seismic exploration within Authority to Prospect (ATP) 423P at the northern margin of the basin was critical to the recognition and definition of the Mount Isa Basin. The northern Mount Isa Basin is structurally analogous to the Palaeozoic Arkoma Basin of Oklahoma and Arkansas in the southern USA but as with all basins it contains unique characteristics, a function of its individual development history. The northern Mount Isa Basin is defined as the basin area northwest of the Mount Gordon Fault.
THE STRUCTURAL ARCHITECTURE OF THE TIMOR SEA, NORTH-WESTERN AUSTRALIA: IMPLICATIONS FOR BASIN DEVELOPMENT AND HYDROCARBON EXPLORATION
Authors: O'Brien G.W. , Etheridge M.A , Willcox J.B. , Morse M. , Symonds P. , Norman C. , Needham D.J.
Published: August 2017

The initial rifting in the Timor Sea, north-western Australia, took place in the Late Devonian to Early Carboniferous, with the development of the NWtrending Petrel Sub-basin. This rift system was compartmentalised by NE-trending accommodation zones which divided the sub-basin into discrete segments. In each segment, a lower plate rift margin, characterised by large displacement, low angle extensional faults, lay opposite an upper plate, or ramp, rift margin, characterised by small displacement, high angle flexural faults. Switching in the 'polarity' of the rift system took place across major, NE-trending accommodation zones.Part of this rift system was overprinted in the Late Carboniferous to Early Permian by the Westralian Super-Basin rift system, which developed on a NE trend, orthogonal to that of the underlying Petrel Sub-basin. The entire Vulcan Sub-basin and Sahul Platform region developed as part of an upper plate rift margin, with the Vulcan Sub-basin probably forming initially as a small flexural feature in the inboard part of the upper plate rift margin. The rift margin consisted of a linked array of NW-trending accommodation zones and NE-trending normal faults; pre-existing, NW-, NE- and NS-trending ?Proterozoic fracture systems controlled, at least to some extent, the geometry of the rift system that developed. The island of Timor probably developed as a major intra-rift high, or possibly a marginal plateaux, at this time. Thermal subsidence phase sedimentation continued until the Late Triassic, resulting in the deposition of 10 to perhaps 14 km of relatively unstructured sediments.Three major reactivation events affected the Timor Sea during the Mesozoic. These were: compression in the Late Triassic to Early Jurassic, extension in the Late Callovian to Early Oxfordian (late Middle to early Late Jurassic) and compression in the Tithonian/Berriasian (Late Jurassic/Early Cretaceous). These events all reactivated the pre-existing ?Proterozoic/ Petrel Sub-basin/Westralian Super-Basin structural architecture in a variety of ways. In the Petrel Sub-basin, reactivation was localised almost exclusively over the lower plate rift margins, leading to the formation of anticlines and ultimately, salt diapirism.In the Vulcan Sub-basin, all of the significant hydrocarbon discoveries appear to be preferentially located either along, or at the intersection of, NW- and NS-trending fault sets with the NE/ENE-trending grain. This is probably because the intersections of these Proterozoic/Late Carboniferous-Early Permian fault sets respond in a particularly complex fashion to the varying Mesozoic stress directions. In a qualitative fashion, this observation does provide a number of largely untested exploration 'fairways' within the Vulcan Sub-basin.
NORTH WEST SHELF 3-D SEISMIC—A DECADE OF DEVELOPMENTS
Authors: Vaughan P.S.
Published: August 2017

Woodside as Operator, on behalf of three Joint Venture groups, over the last decade has acquired eight 3-D seismic surveys covering some 4 600 km2 over the Rankin Trend and Dampier Sub-Basin Production Licences and Exploration Permits on the North West Shelf of Australia. This area represents approximately 45 per cent coverage of the present Woodside operated acreage in the area. The acquisition, processing and interpretation technology and also the benefits derived from the 3-D technique have changed remarkably since the first North West Shelf 3-D survey in 1981. This paper focusses on the main technological developments in 3-D seismic, particularly involving multi-source and streamer technology, increased spatial sampling and interpretation techniques which have changed the role of 3-D seismic in Exploration strategies through the 1980s and into the 1990s.
BEHARRA SPRINGS—FAST TRACK DEVELOPMENT OF A SMALL GAS FIELD UTILISING MEMBRANE SEPARATION TECHNOLOGY
Authors: Heinemann S. B.
Published: August 2017

The Beharra Springs gasfield was discovered in 1991 in EP320 in the northern Perth Basin. Two wells were drilled on the upthrown side of the Beharra Springs Fault and intersected a gas bearing sandstone near the top of the Early Permian Carynginia Formation. Dry gas flowed at 240 000 cubic m3 (8.5 MMscfd) through a (0.5") choke and at 660 000 m3 (23MMscfd) through a 14.3mm (9/16") choke respectively.The gas field sited 1.6 km from the Dongara to Pinjarra WANG pipeline coupled with the market demand from large industrial consumers (Alcoa) provided the necessary components of a low cost fast track development of a relatively small gas deposit.Following production testing trials, process screening studies commenced in May 1991.Front end design activities commenced in August 1991 and by May 1992, some nine months later production of 15 terajoules per day (TJ/d) of pipeline specification gas flowed from the gas field to Alcoa in Pinjarra.The $10 million gas processing and pipeline facilities include:Low temperature dehydration facilities utilising gas expansion cooling (Joule Thompson effect) and heat exchange to reduce gas temperature to -15°cat eight MPa. (Wellhead pressure initially 26 MPa) to ensure the gas meets water and hydrocarbon dew point specification.Semi-permeable membranes, made from thin films of polymer, to reduce the corrosive gases carbon dioxide and hydrogen sulphide form six per cent to 2.5 per cent and 10 ppm to 3.2 ppm respectively to meet pipeline specification. The membranes operate at 7.5 MPa.The use of skid mounted process modules and technology utilising the pressure inherent in the gas field to avoid the use of large rotating equipment and process chemicals were the other essential components utilised in quickly developing the Beharra Springs gas discovery into an efficient gas production facility.
THE STRESS FIELD OF THE NORTH WEST SHELF AND WELLBORE STABILITY
Authors: Millis R.R. , Williams A.F.
Published: August 2017

Boreholes drilled in the search for hydrocarbons in the Barrow-Dampier Sub-Basin (North West Shelf, Australia) commonly exhibit an elliptical cross-section believed to be due to stress-induced wellbore failure known as borehole breakout. The azimuths of the long axes of 138 discrete breakouts identified in nine different wells in the Barrow-Dampier show a consistent 010°−030°N trend implying that maximum horizontal compressive stress is oriented 100°−12G°N.The orientation of horizontal stress determined in this study (and that from the Timor Sea area which is rotated some 50°−60° with respect to the Barrow-Dampier) is consistent with that derived from theoretical modelling of the stress within the Indo-Australian plate based on the plate tectonic forces acting on its boundaries. The rotation of the horizontal stress orientations along the North West Shelf, between the Barrow-Dampier and the Timor Sea, is a reflection of the present-day complex plate convergence system at the north-eastern boundary of the Indo-Australian Plate.Vertical stress magnitudes, Sv, in the Barrow-Dampier were determined from density and sonic log data. Minimum and maximum horizontal stress magnitudes, Shmin and Shmax, were determined from mini-hydraulic fracture (or modified leak-off) test results. These data suggest that the fault condition of the Wanaea/Cossack area is on the boundary between normal faulting (extension) and strike-slip, i.e. Sv ≈ Shmax > Shmin. However, in other parts of the Barrow-Dampier the evidence suggests a strike-slip fault condition, i.e. Shmax > Sv > Shmin.Given the orientation of the stress field and the fault condition, inferences can be drawn regarding the stability of horizontal wells. Furthermore, experience from vertical wells can be utilized to determine the upper and lower bounds to the mud-weight envelope as functions of deviation and wellbore orientation. Since a horizontal well will see Sv and a horizontal stress, stress anisotropy around a wellbore in the Wanaea/Cossack area (and hence wellbore instability) will be minimized by drilling in the Shmin direction i.e. 010°–030°N.
EXPLORATION, ENVIRONMENT AND COMMUNITY EDUCATION
Authors: Cutler Jane
Published: August 2017

BHP Petroleum practice is to undertake a comprehensive environmental management program for exploration activities in environmentally sensitive areas. The planning for the exploration program in the Otway and Duntroon Basins is presented as a case study.BHP Petroleum's exploration activities in the Otway Basin, offshore Victoria, have been the subject of community debate as a result of the perceived effects on sensitive environmental values. The environmental management program undertaken for this exploration project included:a community consultation and information program;development of a geographic information system (GIS) recording a range of environmental and logistical (spill response) information;a whale research program; andformulation and implementation of an environmental management plan.This program and the issues it is designed to address has been an education for the Company, the community and government agencies.
DEALING WITH ROYALTY INTERESTS
Authors: Phillips Craig W. O. , Gibney Marian F.
Published: August 2017

Exploration companies (particularly junior exploration companies) at the time of acquiring acreage under exploration permits, are often required to consider farming out their interests in order to sustain development. In such circumstances, it is usual to retain some form of royalty or carried interest arrangement. However, the form and nature of the interest retained, and the rights and obligations attaching to it are of vital importance in the subsequent development of the acreage. The basic understanding of these arrangements may make the difference between a project being economic or uneconomic. The conference paper proposes to review the different types of royalty or similar interests and their relative advantages and disadvantages. In doing so, it will review some of the more pertinent aspects of Australian and, to some extent, U.S. oil and gas law.
THE TIRRAWARRA OIL FIELD: FIELD REVITALISATION THROUGH RESERVOIR DESCRIPTION AND CHARACTERISATION
Authors: Seggie R.J. , Lansom P.B. , Hamlin H.S. , Johnson G.A.
Published: August 2017

The need for an improved model of the Tirrawarra Oil Field reservoir led to a characterisation project jointly undertaken by SANTOS Ltd and the Bureau of Economic Geology. The objectives of the project were to describe and characterise the geological complexity of the field and within this framework to quantify the residency of the original and remaining oil resource.A detailed facies based flow-unit model was developed, within which petrophysical parameters and pay distribution have been mapped. Four principal facies were identified from which six flow units were characterised in detail. The environments of deposition were shown to control the detailed fabric of the rock, which in turn controls reservoir properties and productivity. The reservoir is interpreted to have been deposited as a braid delta, which has been reworked by a lacustrine shoreface transgressing and regressing across the area in response to rapid and frequent changes in lake level. Consequently, the two main flow units are relatively uniform in character, with much of the production-reducing shale being removed. The new reservoir model provides a greatly improved explanation of field performance, particularly that which was previously considered anomalous. This attests to the reliability of the model for use in reservoir engineering studies and the identification of opportunities for incremental development of the large oil resource remaining in the field.Under-developed portions of the field are now being assessed for miscible flood expansion with the aim of future growth in both oil production and reserves.
SURFACE FACILITIES FOR THE SOUTH WEST QUEENSLAND GAS PROJECT
Authors: Robinson Richard G.
Published: August 2017

The South West Queensland Gas Project is the first greenfield gas development in the Cooper Basin for around 10 years. This has allowed a decade of operating experience from wet gas fields in the region to be applied in the design of the new facility. The design also took into consideration potential future expansion of the facility for increased throughput and the production of sales gas to service markets to the east and north.A greenfield hydrocarbon development in such a remote location is much more than just a gathering system and processing facility. A full range of infrastructure was also developed including telecommunications, roads, airstrip, accommodation and utilities.The project offered opportunities for a wide variety of Australian vendors and construction contractors. Many demonstrated a high level of capability to meet the cost, schedule and quality demands of a hydrocarbon development in the 1990s. Unfortunately, a number failed to demonstrate that capability.
DEVELOPMENT OF WELLBORE TREATMENT TECHNOLOGY FOR IMPROVING PRODUCTION EFFICIENCY FROM AUSTRALIAN OIL AND GAS WELLS
Authors: Rahman M.M. , Khan F.A. , Rahman S.S.
Published: August 2017

Low permeability or formation damage during drilling and completion procedures is often a serious threat to the economic development of a series of Australian oil and gas reserves. In this paper the Pacoota Sandstone in the Amadeus Basin has been considered and the effects of clay mineral morphology, water shock, type and concentration of different salts and varying flow velocity on fines migration were studied. Possible formation damage due to completion fluids and remedial measures such as matrix acidizing were also evaluated.The Pacoota Sandstone has been found to be sensitive to the salt concentration of permeating fluids. If the concentration falls below a threshold value, permeability begins to decrease drastically. Permeability impairment may further be aggravated if the flow rate of the permeating fluid reaches beyond a critical value. It has also been observed that the typical completion fluid reduces the permeability of the near wellbore region to almost half the original permeability. Use of CMHEC base chalk mud, however, reduces the water loss and consequently the permeability impairment by forming an internal filter cake with a typical honeycomb structure. Mud acid with less than 2.5 per cent HF acid concentration has been found to be insufficient to enhance porosity and permeability of the studied sandstone, rather it reduces the permeability by creating formation fines. Afterflush with EGMBE (10 per cent by volume) and HCl acid also helps to clean-up the small fines created during acidizing. The overall increase in porosity and permeability occurs mainly due to formation of large pore channels by matrix dissolution.
DEVELOPMENT PLANNING FOR THE COSSACK AND WANAEA FIELDS
Authors: Salter G. B. , Kerckhoff W. P.
Published: August 2017

Development of the Cossack and Wanaea oil fields is in progress with first oil scheduled for late 1995. Wanaea oil reserves are estimated in the order of 32 x 106m3 (200 MMstb) making this the largest oil field development currently underway in Australia.Development planning for these fields posed a unique set of challenges.Key subsurface uncertainties are the requirement for water injection (Wanaea only) and well numbers. Strategies for managing these uncertainties were studied and appropriate flexibility built-in to planned facilities.Alternative facility concepts including steel/concrete platforms and floating options were studied-the concept selected comprises subsea wells tied-back to production/storage/export facilities on an FPSO located over Wanaea.In view of the high proportion of costs associated with the subsea components, significant effort was focussed on flowline optimisation, simplification and cost reduction. These actions have led to potential major economic benefits.Gas utilisation options included reinjection into the oil reservoirs, export for re-injection into North Rankin or export to shore. The latter requires the installation of an LPG plant onshore and was selected as the simplest, safest and the most economically attractive method.
METAL SEAL WELLHEAD COMPLETION FOR THE ROLLER AND SKATE DEVELOPMENT
Authors: Bottomley C.A.
Published: August 2017

A complete metal sealing surface wellhead and Xmas tree has been designed and installed on the Roller and Skate production facilities. Two sizes of production tree have been utilised: a 5-1/8" tree for Roller and a 4-1/16" for Skate. The production and injection fluids favoured the use of metal seal wellheads. The design facilitated easy and quick makeup with time saving in several areas over a conventional standard elastomer wellhead. The design also provides long term metal sealing assurance. Based on research and to the knowledge of the writer, these completions are the first complete all-metal sealing surface wellheads installed in Australia.
AUSTRALIA'S FIRST SAFETY CASE
Authors: Kratzing D.C. , Moorefield D. , Coghlan P.
Published: August 2017

Significant changes have occurred to the Australian offshore legislative approach to safety following the Piper Alpha disaster and the COSOP Report. Operators of new facilities are now required to demonstrate that they have addressed all of their safety obligations through the preparation of a Safety Case.This paper outlines the new legislative responsibilities and describes the preparation and assessment of the Design and Operational Safety Cases for the Wandoo Production Test. Their format and content are presented, and some of the benefits and difficulties associated with both the preparation and review are discussed.These Safety Cases are the first considered under the new Australian legislation.
PETROLEUM SOURCE ROCKS IN THE ROPER GROUP OF THE MCARTHUR BASIN: SOURCE CHARACTERISATION AND MATURITY DETERMINATIONS USING PHYSICAL AND CHEMICAL METHODS
Authors: Taylor Dennis , Kontorovich Aleksai E. , Larichev Andrei I. , Glikson Miryam
Published: August 2017

Organic rich shale units ranging up to 350 m in thickness with total organic carbon (TOC) values generally between one and ten per cent are present at several stratigraphic levels in the upper part of the Carpentarian Roper Group. Considerable variation in depositional environment is suggested by large differences in carbon:sulphur ratios and trace metal contents at different stratigraphic levels, but all of the preserved organic matter appears to be algal-sourced and hydrogen-rich. Conventional Rock-Eval pyrolysis indicates that a type I-II kerogen is present throughout.The elemental chemistry of this kerogen, shows a unique chemical evolution pathway on the ternary C:H:ONS diagram which differs from standard pathways followed by younger kerogens, suggesting that the maturation histories of Proterozoic basins may differ significantly from those of younger oil and gas producing basins. Extractable organic matter (EOM) from Roper Group source rocks shows a chemical evolution from polar rich to saturate rich with increasing maturity. Alginite reflectance increases in stepwise fashion through the zone of oil and gas generation, and then increases rapidly at higher levels of maturation. The increase in alginite reflectance with depth or proximity to sill contacts is lognormal.The area explored by Pacific Oil and Gas includes a northern area where the Velkerri Formation is within the zone of peak oil generation and the Kyalla Member is immature, and a southern area, the Beetaloo sub-basin, where the zone of peak oil generation is within the Kyalla Member. Most oil generation within the basin followed significant folding and faulting of the Roper Group.
DETERMINATION FROM WELL LOGS OF THE TOTAL ORGANIC CARBON CONTENT IN POTENTIAL SOURCE ROCKS
Authors: Lin J.L. , Salisch H.A.
Published: August 2017

This paper discusses, in some detail, the log responses to total organic carbon (TOC) in the Upper and Middle Velkerri Formation in an area of the McArthur Basin, Northern Territory, Australia. The Formation Density log was found to be superior to other standard well logs in assessing values of TOC in the area studied. A theoretical model was used to estimate TOC from the Formation Density log. The model was established and its applicability was verified by comparison with other models. Based on geochemical properties the Upper and Middle Velkerri Formation is classified into three categories: nonsource rocks, mature source rocks and immature source rock. They show significant differences in the well log responses, and different models had to be established for the three categories to determine the TOC content from well logs. Comparison of the results of using a different model for each category instead of a single model to cover the three categories shows that the former approach gives more meaningful answers.
SEDIMENTARY PROVENANCE STUDIES IN AUSTRALIAN BASINS USING NEODYMIUM MODEL AGES
Authors: Whitford D. J. , Hamilton P.J. , Scott J.
Published: August 2017

An understanding of the tinting of basin evolution is fundamental to the development of successful play concepts. The Sm-Nd geochronometer can be used to determine quantitatively the `average' age at which segments of continental crust have been extracted from the earth's mantle. Variations in Nd model ages within sedimentary rock sequences indicate changes in sedimentary provenance over time and provide a potential correlation tool.In the Eromanga Basin, there is a distinct lithological contrast between the main reservoir unit, the Jurassic Hutton Sandstone, and the overlying Birkhead Formation. The quartz-rich Hutton Sandstone is characterised by relatively old Nd model ages, generally within the range 1.3–1.5 Ga. In contrast the lithic-rich Birkhead Formation has much younger model ages, generally Neodymium model ages measured in mudstones within the Flag Sandstone from the Harriet Field in the Barrow Sub-basin of the North West Shelf, range from 2.1–2.5 Ga. The old ages are consistent with the sediments being derived from the Archaean shield areas and the younger Proterozoic complexes of Western Australia. Tentative correlations based on model ages between mudstone units from two wells are consistent with correlations based on heavy mineral suites.Neodymium model ages have application to correlation at both regional and local scales within basins. Reliable information can be obtained on both sandstones and mudstones on samples as small 50 g. Potentially they can provide important quantitative information complementary to that derived from more conventional approaches.
TWO AND THREE DIMENSIONAL ANALOGUE MODELLING OF EXTENSIONAL FAULT SYSTEMS WITH APPLICATION TO THE NORTH WEST SHELF, WESTERN AUSTRALIA.
Authors: Lemon N. M. , Mahmood T.
Published: August 2017

The North West Shelf of Western Australia is an area of known extensional control with a number of inbuilt complexities related to variations in direction of extension and the existence of early fracture sets. Analogue modelling in a sandbox of modest construction and proportions can imitate the style of structures imaged by seismic on the North West Shelf. Models were constructed to simulate deformation in a sedimentary sequence above simple listric, ramp/flat and complex 3D detachment surfaces. A new 3D technique has been devised to simulate progressive deformation above complex detachment morphologies. Analysis of the structures produced has been achieved by marrying sequential plan view photographs of the model surface with serial vertical sections of the bulk of the model once the experiment has been completed and the sand stabilised. This technique also has the ability to simulate geometry and kinematics of extensional structures in a complex polyphase area. This 3D technique has proven particularly useful in the understanding of structures developed in regions where the sedimentary sequence has been subject to more than one period of extension, each with different orientations. The models provide the first understanding of the areal distribution of fault patterns and associated subsidiary troughs in areas of complex detachments. These models show the distribution of pre-rift and syn-rift sediments in extensional terranes and are valuable in the prediction of deformation in areas of poor seismic quality and for confirmation of seismic interpretation.
WANDOO—A NEW TREND
Authors: Delfos Ernie , Boardman Malcolm
Published: August 2017

In June 1991 a flow of 4 560 barrels of 19° API oil per day, from a depth of 600 m, heralded the discovery of a new hydrocarbon trend along the eastern margin of the Dampier Sub-basin on the North West Shelf of Australia. Wandoo–1 recovered oil and gas from lower Cretaceous sands associated with the M.australis dinoflagellate zone (Barremian), and gas from lower Jurassic Aalenian sands.The main reservoir at Wandoo is the M. australis Sandstone Member of the Muderong Shale. This is interpreted to be a shelfal shoal sand deposited in a minor regression phase during the regional transgression of the Muderong Shale. This reservoir is split into two main lithotypes, a glauconitic subarkose to subarenite, and an overlying greensand. Oil and gas have been recovered from both units, which are considered contiguous for reservoir definition. General reservoir parameters are exceptional. Since the initial discovery a 3D seismic survey has been acquired and appraisal drilling has proven approximately 250 MMSTBOIP.The unusual features of the field necessitated innovative exploration techniques and the need for a strong appraisal program. These techniques included a six streamer, high resolution, three dimensional seismic survey and its associated processing; development of methods to recover and preserve core in extremely unconsolidated sediments; use of non destructive core analysis methods such as nuclear magnetic resonance; and petrophysical analysis that incorporates the resistivity suppression problems of glauconite. Without core a very pessimistic view would have been taken of the M. australis Sandstone reservoir.The Wandoo discovery is on an exciting new trend previously overlooked due to the shallowness of reservoirs, lack of locally recognised source rocks and the dominance of other oil and gas trends in the Dampier Sub-basin and Barrow Sub-basin to the south.
THE ROLE OF THE PRE-RIFT STRUCTURE IN THE ARCHITECTURE OF THE DAMPIER BASIN AREA, NORTH WEST SHELF, AUSTRALIA
Authors: Hill Geoff
Published: August 2017

The Dampier Sub-basin shows many faults oblique to the basin axis. Previous explanations for this range from syn-rift transfer systems through to deep seated wrenching.Multiple rift episodes, with differing stress directions, occur in the area's history, each utilising the pre-existing fault patterns. As basement is difficult to interpret beneath thick sedimentary cover, the initial architecture is interpreted from the tectonic setting.The sub-basin lies adjacent to the Archean Pilbara Craton, a stable crustal block surrounded by ancient mobile belts. The East Africa rift system has also formed in a Craton margin setting. In East Africa earthquake data and detailed seismic interpretation show the rift utilises faults within the mobile belt systems.In the Dampier area, the three different extension vectors combined with the pre-rift fabric and the East Africa analogue, are used to build an alternate model for the basin genesis. Permo-Carboniferous extension sets up a rift system partitioned by the Precambrian fabric. Jurassic extension reactivates these faults but with oblique slip and dip slip movement caused by the new extension direction. This oblique slip causes complex branching arrays of new faults within the cover section. A third extension vector in the Cretaceous subsequently modifies the fabric. The Dampier Sub-basin is seen as a complex failed rift utilising a Precambrian tectonic fabric. The structural inheritance of the pre-rift fabric by each rift episode has affected the geometry of hydrocarbon-bearing structures of the sub-basin.
HYDROCARBON POTENTIAL OF THE BATHURST ISLAND GROUP, NORTHEAST BONAPARTE BASIN, IMPLICATIONS FOR FUTURE EXPLORATION
Authors: West B.G. , Passmore V.L.
Published: August 2017

Despite 20 years of exploration between 1965 and 1992 in the northeastern part of the Bonaparte Basin, the region remains underexplored. Exploration has produced modest encouragement. The seven wells drilled in the area totalling more than 70 000 km2 include one dry gas and two gas/condensate discoveries. Explorers have targeted the Jurassic Plover Formation and Flamingo Group, but reservoir quality has often been poor in both units due largely to depth of burial.Recent regional studies of the northeastern part of the Bonaparte Basin, undertaken by the Bureau of Resource Sciences, indicate there is potential for generation and entrapment of hydrocarbons in the Cretaceous Bathurst Island Group. Geochemical results show the lower Bathurst Island Group contains good source rocks that are largely gas prone, but have the potential to charge large Cretaceous traps. Geohistory modelling suggests that the Bathurst Island Group may have entered the oil window around the Middle Cretaceous, after most of the structuring had occurred, and continued until the Middle Miocene or later. Potential reservoirs have been identified in Santonian, Campanian and Maastrichtian sands, and in fractured Albian Carbonates.Recent reports have predicted that by early next century there will be a significant increase in natural gas consumption in Australia, due to increased use for power generation and transportation, as well as further sales to the Asian market. New methanol technology could commercialise some marginal gas fields. The theme for this years APEA conference is `New Age—New Opportunities'. The Bonaparte Basin may provide the opportunity to explore for and develop new gas accumulations.
STRATEGY AND VALUATION PITFALLS IN NORTH AMERICA
Authors: Caldwell R.H.
Published: August 2017

The statement Australian oil companies who venture into North America end up losing their shirts is a truism to many. It can be shown that companies who execute strategies based on the fundamental recognition of business, market and risk aspects particular to the mature nature of the US oil industry are successful. Such strategies, and the associated pitfalls are discussed and illustrated using industry norm data.
INTERNATIONAL CLIMATE CHANGE: POLICY AND ACTION
Authors: Beck Dr Tony
Published: August 2017

The Framework Convention on Climate Change, first negotiated at the Rio 'Earth Summit', has recently been ratified by the required 50 countries. Now that the Convention has come into force the pace of implementation will quicken with important implications for Australia and world trade. Developed countries, including Australia, are likely to be under significant pressure to strengthen the emission control commitments they made at Rio.For a country like Australia with growing energy demand and a dependence on fossil fuels, the potential costs of meeting stringent greenhouse emission constraints are high, both in terms of domestic economic costs and lost export markets. We need to be vigilant with respect to policy developments in other countries and need to ensure that domestic greenhouse policies are appropriate to our circumstances.The recent International Negotiating Committee (INC9) meeting in Geneva gives an indication of the direction of international policy developments and a forewarning of the potential dangers for Australia. This paper reviews the outcomes of INC9 and considers the implications of these developments for Australia.
A COMPARISON OF PHYSICAL MODEL WITH FIELD DATA OVER OLIVER FIELD, VULCAN GRABEN
Authors: Evans B.J. , Oke B.F. , Urosevic M. , Chakraborty K.
Published: August 2017

Physical models representing the three dimensional geology of oil fields can be built from materials such as plastics and resins. Using ultrasound transmitters and receivers, 2D and 3D seismic surveys can be simulated to aid in the survey design of field work, provide insight into data processing, and can test interpretation concepts. Such modelling simulates most aspects of both land and marine seismic.In 1993 BHP Petroleum, on behalf of the AC/P6 Joint Venture, contracted Curtin University's Geophysics Group to build a 1:40,000 scale, 11-layer, 2.5D model of the Oliver Field so that 2D and 3D field data acquisition and processing could be simulated. A 2.5D model is invariant in the strike direction, but can answer most of the questions of a true 3D model at a fraction of the effort and cost. This was the first such model built in Australia, and one of the most complex physical models ever built.Of interest was the quality of imaging under the fault shadow near reservoir level, and whether the application of dip or strike 3D acquisition and processing approaches could improve the seismic data quality. Consequently, both dip (2D) and strike (2.5D) seismic data were acquired over the model using similar parameters to those used in conventional offshore acquisition. The data were processed to migration stage and compared with the field seismic data. Numerical model and field VSP data were also processed and compared with the field and physical model seismic data.The good agreement between processed physical model seismic and field seismic shows that physical modelling of geology has application in both two and three dimensional interpretation, acquisition planning, and processing testing and optimisation.This physical model experiment proved conclusively that shallow faults with a relatively large velocity contrast across them cause 'back' faults on the seismic data which do not exist in reality. Furthermore, this experiment proved for the first time using a physical model that strike 3D marine recording is preferable to dip 3D marine recording.
GEOPHYSICAL OPTIMISATION OF THE MACKEREL FIELD RE-DEVELOPMENT—GIPPSLAND BASIN, AUSTRALIA
Authors: Cousins M.G.
Published: August 2017

Mackerel, the third largest oil field in the Gippsland Basin, is a mature field with over 80 per cent of reserves produced from 18 original development wells.The initial Mackerel development was based on a fairly simplistic reservoir model incorporating the results of the four exploration wells. The net to gross was anticipated at 90 per cent throughout the reservoir and no significant permeability barriers were expected. After 10 years of production a review of field performance indicated the reservoir was not as homogenous as first anticipated.Redevelopment of the Mackerel Field began in 1990 following the acquisition of the first of two high resolution 3D surveys and culminated in the drilling of 18 additional wells from the Mackerel platform during 1993 and 1994. It was these 3D surveys which changed the entire reservoir model of Mackerel to one of a far more compartmentalised nature.Seismic attribute analysis, when calibrated to 2D forward modelling was used to predict intra-reservoir seals and the distribution of poorer quality reservoir; both not previously recognised over the field. The truncation points of the intra-reservoir seals against the main field-wide trapping unconformity were accurately mapped using seismic attributes and image enhancement techniques such as ER Mapper. Previously undetectable fault extensions, with throw around 10 m, can act as partial flow barriers and were recognised for the first time via 'sun-angle illumination' of azimuth maps. This allowed optimum well placement and helped explain historical field performance. Horizon slicing techniques and the calibration of volume attributes were used to establish depositional environments and seal capacity of the predicted intra-reservoir seals.The drilling results have shown that over the production life of the Mackerel Field the reservoir consists of a number of drainage compartments, each separated by seismically resolvable intra-reservoir seals.The redevelopment of the Mackerel field increased production rate by 18 thousand barrels per day (kBD) in 1993, and proved additional capture reserves of which approximately 40 percent can be directly attributed to the 3D seismic data and the applied interpretation techniques.