SEAL POTENTIAL IN CRETACEOUS AND LATE JURASSIC ROCKS OF THE VULCAN SUB-BASIN, NORTH WEST SHELF AUSTRALIA

2002 ◽  
Vol 42 (1) ◽  
pp. 203 ◽  
Author(s):  
T. Kivior ◽  
J.G. Kaldi ◽  
S.C. Lang
Keyword(s):  
Data Quality ◽  
Late Jurassic ◽  
Column Height ◽  
Areal Extent ◽  
North West ◽  
Sequence Stratigraphic ◽  
Seal Integrity ◽  
Almost All ◽  
Rock Mechanical Properties ◽  
Mercury Injection Capillary Pressure

The occurrence of palaeo-oil columns in Late Jurassic and Cretaceous reservoirs in the Vulcan Sub-basin suggests that hydrocarbon accumulations have leaked. It is unclear whether accumulations have leaked through breach of top seal or fault seal. This paper evaluates the top seal potential for hydrocarbon accumulations in the Vulcan Sub-basin. Seal potential (SP) combines seal capacity (the hydrocarbon column height that can physically be held back by a seal), seal geometry (the areal extent and thickness of the seal) and seal integrity (rock mechanical properties of the seal). Seal capacities are measured using mercury injection capillary pressure calculations. Areal extent is evaluated using sedimentological and sequence stratigraphic principles. Thickness is determined empirically from well logs and seismic data. Seal integrity is derived from a brittleness index. In addition, a component relating to data quality and quantity is included in seal potential evaluation.Lower Vulcan Formation SP ranges from low to high due to variations in seal capacity and thickness risks as well as data quality and quantity. High SP occurs in the main depocentres and low SP occurs on palaeo-highs and basin margins. Upper Vulcan Formation SP ranges from low to moderate due to variations in seal capacity and data issues. Moderate SP occurs in depocentres and low SP on basin margins. In the Echuca Shoals Formation seal capacity, seal extent and integrity as well as data quality and quantity are good. Seal thickness, however, is inconsistent, resulting in SP variations from good to poor as a function of thickness. Jamieson Formation has high seal capacities, is thick and areally extensive. The seal potential, however, is locally moderate (e.g. on the Ashmore Platform) due to integrity issues. Woolaston, Gibson and Fenelon (WGF) Formations are grouped together as the regional seal and in this group SP varies from low to high. The WGF rocks have high seal capacities, are areally extensive and thick and the data quality and quantity is good. The main risk is integrity, which increases from northwest to southeast in the basin.Based on the overall seal potential analyses, almost all seals in the area are capable of holding back hydrocarbon columns greater than present or paleocolumns encountered. This suggests that hydrocarbon leakage in the Vulcan Sub-basin was unlikely to have occurred as a result of top seal capillary failure.

The Roebuck Basin, Beagle and Barcoo Sub-basin well folio

2019 ◽  
Vol 59 (2) ◽  
pp. 920 ◽  
Author(s):  
Duy Nguyen ◽  
Nadege Rollet ◽  
Emmanuelle Grosjean ◽  
Dianne S. Edwards ◽  
Steve Abbott ◽  
...  
Keyword(s):  
Lower Cretaceous ◽  
Geochemical Data ◽  
Well Log ◽  
North West ◽  
Sequence Stratigraphic ◽  
Seal Integrity ◽  
Critical Issues ◽  
Secondary Objective ◽  
And Migration ◽  
Migration Pathways

The Roebuck Basin and the adjoining Beagle and Barcoo sub-basins are underexplored areas on Australia’s North West Shelf that are undergoing renewed exploration interest since the discovery of oil at Phoenix South 1 in 2014 and subsequent hydrocarbon discoveries in the Bedout Sub-basin. A well folio of 24 offshore wells across the Beagle, Bedout, Rowley and Barcoo sub-basins has been compiled as part of Geoscience Australia’s hydrocarbon prospectivity assessment across the region. It consists of composite well log plots and well correlations that summarise lithology, lithostratigraphy, Geoscience Australia’s newly acquired biostratigraphic and geochemical data as well as results of petrophysical analysis. A revised sequence-stratigraphic interpretation, key petroleum system elements and drilling results are also documented. The wells dominantly target Triassic shoreward facies (Keraudren Formation) as the primary reservoir objective and Jurassic fluvial-deltaic (Depuch Formation) and/or Lower Cretaceous sandy deltaic facies as the secondary objective. The Keraudren Formation sandstones are sealed intra-formationally either by discontinuous units and/or by the regional Cossigny Member. The Jurassic Depuch Formation sandstones are sealed by regional Lower Cretaceous mudstones. Both charge and structure have been identified as critical issues in the Roebuck Basin. In the Beagle Sub-basin, seal integrity and migration pathways are also considered high risk. Well correlations have identified differences in the basin history and provide insights into the distribution of facies and other characteristics of the Jurassic and Triassic successions.

United Front: Partisans of the Leningrad Region and their connections with the Central Asian Soviet Republics

2021 ◽  
Vol 2021 (02) ◽  
pp. 214-225
Author(s):  
Sergey Kulik ◽  
Аnatoliy Kashevarov ◽  
Zamira Ishankhodjaeva
Keyword(s):  
World War Ii ◽  
Weather Conditions ◽  
Leningrad Region ◽  
World War ◽  
North West ◽  
The North ◽  
Occupied Territory ◽  
Central Asian ◽  
The Difference ◽  
Almost All

During World War II, representatives of almost all the Soviet Republics fought in partisan detachments in the occupied territory of the Leningrad Region. Among them were many representatives of the Central Asian republics: Kazakhstan, Kyrgyzstan and Uzbekistan. Many Leningrad citizens, including relatives of partisans, had been evacuated to Central Asia by that time. However, representatives of Asian workers’ collectives came to meet with the partisans. The huge distance, the difference in cultures and even completely different weather conditions did not become an obstacle to those patriots-Turkestanis who joined the resistance forces in the North-West of Russia.

An Integrated Petrophysical Workflow for Fluid Characterization and Contacts Identification Using NMR Continuous and Stationary Measurements in a High-Porosity Sandstone Formation, Offshore Norway

2021 ◽  
Vol 62 (2) ◽  
pp. 210-226
Author(s):  
Maciej Kozlowski ◽  
◽  
Diptaroop Chakraborty ◽  
Venkat Jambunathan ◽  
Peyton Lowrey ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Data Quality ◽  
Spin Relaxation ◽  
North Sea ◽  
Column Height ◽  
Reservoir Quality ◽  
Formation Evaluation ◽  
The North ◽  
Nmr Data ◽  
Fluid Properties

The Alvheim Field in the Norwegian North Sea was discovered in 1998. Two wells were drilled in 2018 in the Gekko structure to confirm oil column height and to evaluate reservoir quality in the Heimdal Formation. A comprehensive wireline logging program, including NMR and formation testing, was optimized to reduce formation evaluation uncertainty. Evaluating fluid properties, oil column height, and reservoir quality were primary objectives. Well A was first drilled on the south of the structure, followed by Well B on the north of the structure. Reservoir quality encountered in both wells was very good, and a project to develop these resources is currently in the selection phase. Formation evaluation uncertainty encompassing pore geometry distribution, permeability, reservoir quality, and hydrocarbon identification are mitigated by studying the nuclear magnetic resonance (NMR) log response. NMR fluid typing has been widely used in the oil industry since the 1990s. NMR fluid typing today is a combination of the contrast of spin relaxation time T1, the spin-spin relaxation time T2 (T1T2), and the diffusivity (T2D) of formation fluids (Chen et al., 2016). NMR fluid typing can be obtained from a continuous log and/or stationary log measurements. This paper showcases excellent, textbook-quality NMR data, as well as the integration of NMR data in the petrophysical workflow. High-confidence fluid properties and fluid contacts are determined. This paper also highlights a comparison of NMR data acquired in stationary vs. continuous depth-based log modes in both wells. The continuous log data quality is equivalent to stationary data, implying continuous log data quality is sufficient for reliable NMR fluid properties evaluation without depending on time-consuming stationary NMR measurements. Reducing logging operations rig time is very advantageous in the North Sea, where drilling rig operations cost is high, and enhanced rig time management is constantly required.

Dispersal of Silver Gulls, Larus novaehollandiae Stephens, from Breeding Colonies in South Australia

1985 ◽  
Vol 12 (2) ◽  
pp. 279 ◽  
Author(s):  
JR Ottaway ◽  
R Carrick ◽  
MD Murray
Keyword(s):  
South Australia ◽  
High Status ◽  
Dispersal Patterns ◽  
North West ◽  
Significant Difference ◽  
Rubbish Dumps ◽  
The Difference ◽  
Dispersal Distances ◽  
Almost All ◽  
The City

Dispersal of Larus novaehollandiae Stephens, from 10 colonies in South Australia, was studied during 1968-8 1 by means of bands designed for identification of free-living, uncaptured individuals. Dispersal patterns were characteristic of each colony, even for three colonies which were, at most, 10 km apart. Almost all dispersal records came from the area between Adelaide and Melbourne, and within 30 km of the coast. After breeding, the majority of gulls disperse eastwards; however, dispersal from each colony was correlated with a shift of gull population into areas where food was available from human sources such as rubbish dumps. From colonies 80 km south-east of Adelaide, a major human population, the predominant winter dispersal of these gulls was north-west, into the city and suburbs. The maximum direct-line dispersal distances recorded for 95% of the 3133 resighted gulls were <458 km. The greatest direct-line distance recorded was 1430 km. Overall, there was no significant difference in the mean dispersal distances of juveniles and adults, although at distances >480 km significantly more juveniles (<2y) were seen than adults (>2y). This involved only 2.5% of the total number of birds resighted. It is suggested that older, dominant birds maintain high status at preferred feeding places, and juveniles are possibly more erratic in their movements, as they search for food. This would account for the difference in the dispersal ofjuveniles and adults from a particular colony, and also for the significantly higher proportion of juveniles found at extreme distances from their natal colonies.

Dinoflagellate cysts from an allochthonous block of Nordenskjöld Formation (Upper Jurassic), north-west James Ross Island

1992 ◽  
Vol 4 (3) ◽  
pp. 267-278 ◽  
Author(s):  
Michael G. Snape
Keyword(s):  
New Species ◽  
Papua New Guinea ◽  
Antarctic Peninsula ◽  
Late Jurassic ◽  
New Genus ◽  
Upper Jurassic ◽  
Dinoflagellate Cysts ◽  
Dinoflagellate Cyst ◽  
North West ◽  
James Ross Island

An allochthonous block of the Nordenskjöld Formation from north-west James Ross Island, Antarctic Peninsula has yielded a diverse marine palynoflora. Dinoflagellate cyst assemblages from the 185 m thick sequence are described and compared with similar microfloras previously described from Australia, Papua New Guinea and Madagascar. A mid Tithonian (Late Jurassic) age is suggested for the section. One new genus, Helbydinium gen. nov. and four new species, Helbydinium scabratum sp. nov., Leptodinium acneum sp. nov., Leptodinium posterosulcatum sp. nov. and Rhynchodiniopsis foveata sp. nov. are described.

Late Jurassic (Kimmeridgian-Tithonian) macrofossil assemblage from Jason Peninsula, Graham Land: evidence for a significant northward extension of the Latady Formation

1997 ◽  
Vol 9 (4) ◽  
pp. 434-442 ◽  
Author(s):  
T.R. Riley ◽  
J.A. Crame ◽  
M.R.A. Thomson ◽  
D.J. Cantrill
Keyword(s):  
Antarctic Peninsula ◽  
Late Jurassic ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Coarse Grained ◽  
Areal Extent ◽  
South Eastern ◽  
Back Arc ◽  
The Antarctic ◽  
Major Sequence

New exposures of fossiliferous sedimentary rocks at Cape Framnes, Jason Peninsula (65°57′S, 60°33′W) are assigned to the Middle–Late Jurassic Latady Formation of the south-eastern Antarctic Peninsula region. A sequence of fine to coarse-grained sandstones of unknown thickness has yielded a molluscan and plant macrofossil assemblage rich in the following elements: perisphinctid ammonites, belemnopseid belemnites, oxytomid, trigoniid and astartid bivalves, and bennettitalean fronds and fructifications. The overwhelming age affinities are with the Kimmeridgian–early Tithonian part of the Latady Formation, as exposed on the Orville and Lassiter coasts. The Cape Framnes sedimentary rocks help to constrain the age of a major sequence of acid volcanic rocks on Jason Peninsula, and show that the Latady Basin was geographically much more extensive than recognized previously. It was the principal depositional centre of Middle–Late Jurassic sedimentation in the Antarctic Peninsula back-arc region and in areal extent may have rivalled the essentially Cretaceous Larsen Basin.

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