CARPENTARIA BASIN: A REGIONAL ANALYSIS WITH REFERENCE TO HYDROCARBON POTENTIAL

1984 ◽  
Vol 24 (1) ◽  
pp. 7 ◽  
Author(s):  
I. R. Burgess
Keyword(s):  
Regional Analysis ◽  
Northern Territory ◽  
Primary Objective ◽  
Western Boundary ◽  
Hydrocarbon Generation ◽  
The West ◽  
Clastic Sediments ◽  
Oil Expulsion ◽  
Reservoir Potential ◽  
Territory Border

The Carpentaria Basin is an epeirogenic intracratonic downwarping which formed during the Mesozoic. It is the northernmost of three main Jurassic-Cretaceous downwarps forming the Great Australian Artesian Basin. The basin is filled with clastic sediments, predominantly derived from Precambrian ridges on the flanks of the basin, which thicken gradually from the basin margins towards the depocentre.The Carpentaria Basin is analogous to the Eromanga Basin immediately to the south, and several rock units were deposited contemporaneously in both basins so that they can be mapped in the subsurface from one basin to the next. There is no change in sedimentary style or lithology.The character of the Base Mesozoic Unconformity, over which the Carpentaria Basin was deposited, changes abruptly from east to west. East of a point approximately coincident with the Queensland-Northern Territory border the unconformity surface is flat and featureless but to the west it becomes very rugged and irregular. This rugged horizon is believed to reflect either ancient karst topography or extensive reefal build-up equivalent to dolomite intersected in Burketown 1. Based on correlations with the McArthur and Georgina Basins it is probably Cambrian or Proterozoic in age. These rocks are known elsewhere to be porous and permeable.The unconformity shelves to the west towards Groote Island and the Northern Territory mainland and sediments of the Carpentaria Basin onlap a shallowing ancient landscape. The western boundary of the basin believed to be prospective for hydrocarbons is taken as the limit of deposition of the Cretaceous Gilbert River Formation.Lithologies and the existence of aquifers in the onshore Carpentaria Basin indicate that suitable reservoirs are present. Sandstones in the Cretaceous Gilbert River Formation, the Jurassic Eulo Queen Group and the Hutton Sandstone have the best reservoir potential. The Gilbert River Formation is the primary objective because it was extensively deposited throughout the basin, whereas Jurassic sandstones are restricted to topographic lows.The Gilbert River Formation is sourced and sealed by shales of the Wallumbilla Formation. Onshore this formation is too shallow to be mature but seismic indicates that offshore it is sufficiently deeply buried to be producing and expelling hydrocarbons.The hydrocarbon prospects of the Carpentaria Basin have in the past been considered low because the Mesozoic sequence onshore is thin and even offshore the total thickness of Mesozic and Cainozoic sediments is only about 1760 m at its maximum. This judgement ignored the fact that, although no economic hydrocarbon discoveries have been recorded from the Carpentaria Basin and/or the underlying Palaeozoic Basins, several shows have been reported. Shows reported in onshore wells suggest hydrocarbon generation within the basin. Geochemical and palynological studies carried out on samples from onshore wells and bores indicate the basal Mesozoic sequence is within geochemical Zone II, where the actual generation of hydrocarbons occurs but where significant mobilization and effective oil expulsion do not take place. These data suggest the deeper offshore portion of the basin should be within the oil window.

scholarly journals Petrophysical properties of bypassed Cenozoic clastic reservoirs in the Cesar sub-basin, Colombia

2021 ◽  
Vol 25 (3) ◽  
pp. 275-284
Author(s):  
Helmer Fernando Alarcón Olave ◽  
Edwar Hernando Herrera Otero
Keyword(s):  
Effective Porosity ◽  
Coal Bed ◽  
Hydrocarbon Generation ◽  
Oil Saturation ◽  
Reservoir Rocks ◽  
Volume Porosity ◽  
And Migration ◽  
Oil Expulsion ◽  
Clastic Reservoirs ◽  
Reservoir Potential

The Cesar-Ranchería basin has all the necessary elements for the generation, expulsion, and migration of hydrocarbons and considerable potential for coal bed methane (CBM) in Colombia. Previous studies in the Cesar basin focused on understanding the tectonic evolution, stratigraphy, hydrocarbon generation potential, and evaluation of reservoir potential in Cretaceous calcareous units and quartzose sandstones from the Paleocene Barco Formation. These studies had confirmed the existence of an effective petroleum system, with several episodes of oil expulsion and re-emigration in the Miocene period, turning the Cenozoic clastic succession (Barco, Los Cuervos, La Loma, and Cuesta formations) into an element of significant exploratory interest to clarify the potentiality of the basin in terms of hydrocarbon accumulation. The petrophysical parameters of Cenozoic units (shale volume, porosity, water, and oil saturation) were determined by integrating wells log and core samples analyses from three stratigraphic wells. The integration of these results synthesizes the petrophysical behavior of the units. It defines intervals with clay volumes of less than 30%, effective porosity around 20%, which means favorable characteristics as reservoir rocks that need to be considered in future exploratory projects.

Investigation into the diet of the central rock-rat (Zyzomys pedunculatus)

2003 ◽  
Vol 30 (5) ◽  
pp. 513 ◽  
Author(s):  
Theresa J. Nano ◽  
Cate M. Smith ◽  
Elizabeth Jefferys
Keyword(s):  
Sample Size ◽  
Conservation Status ◽  
Microscopic Analysis ◽  
Faecal Pellet ◽  
Northern Territory ◽  
The West ◽  
Major Food ◽  
Seasonal Shift ◽  
Leaf Consumption

The diet of the rare central rock-rat, Zyzomys pedunculatus, was assessed by microscopic analysis of 18 faecal pellet samples collected from four different sites in the west MacDonnell Ranges in the Northern Territory. Samples were collected from the four sites in summer (n = 13), one site in winter (n = 3), and two sites in spring (n = 2). Four major food categories were observed in the samples: seed, leaf, stem and insect. Seed was by far the most dominant food in the overall diet of Z. pedunculatus, making up 72% of identifiable particles, leaf was secondary (21%), while stem and insects contributed only 3% and 4% respectively. Although the sample size was small, no major seasonal shift between seed and invertebrate dominance was evident. Seed dominated the diet in both summer and winter, though winter seed consumption was lower (78% v. 58%). The level of seed consumption in the two spring samples was highly divergent (38% v. 93%), stressing the need for more samples to be collected from dry periods. Lowered rates of seed consumption during winter and in one of the spring samples were accompanied by increases in leaf consumption. Insect consumption remained low across all sampled seasons, suggesting that this species is not an omnivore. Rather, the dominance of seed in the diet suggests that Z. pedunculatus is primarily a granivore, a finding that has implications for the conservation status and management of this little-known species.

Middle, Upper Jurassic and Lower Cretaceous sedimentary environments of the Djebel Nefusa region, northwestern Libya

1977 ◽  
Vol 8 ◽  
pp. 45-49
Author(s):  
Richard J. Hodgkinson ◽  
Christopher D. Walley
Keyword(s):  
Sedimentary Basin ◽  
Upper Jurassic ◽  
Fault Scarp ◽  
The West ◽  
Sedimentary Environments ◽  
The North ◽  
Clastic Sediments ◽  
Stratigraphic Nomenclature ◽  
Saharan Platform ◽  
North Western

Carbonate and clastic sediments of Jurassic and Cretaceous age are exposed along the fault-scarp of Djebel Nefusa in north-western Libya. Previous geological investigations have been mainly restricted to the eastern sector of the scarp. Recent studies by the authors in the western sector of Djebel Nefusa and on equivalent sediments in southern Tunisia have allowed the first regional interpretation of these rocks.The area studied lies geographically and geologically at the edge of the Saharan Platform, a large cratonic block, composed of rocks of Precambrian-Palaeozoic age. To the north and east lies a downfaulted sedimentary basin (Gabes-Sabratha Basin) containing a large thickness of Mesozoic sediments. The location of the sections measured along Djebel Nefusa are depicted in Fig.1.The stratigraphic nomenclature of the rock succession of Djebel Nefusa was first established in the east and continued laterally towards the west by later workers. Difficulties in the application of this nomenclature are presented by the recognition of facies changes previously overlooked by earlier investigators. However, as a framework for understanding these changes and the sedimentary processes which caused them, the stratigraphy erected by Magnier (1963) is adopted.

SOUTHERN GEORGINA BASIN: A NEW PERSPECTIVE

1990 ◽  
Vol 30 (1) ◽  
pp. 137 ◽  
Author(s):  
W.R. Lodwick ◽  
J.F. Lindsay
Keyword(s):  
Mirror Image ◽  
Source Rocks ◽  
Carbonate Production ◽  
Northern Margin ◽  
Middle Ordovician ◽  
Upper Proterozoic ◽  
Clastic Sediments ◽  
Early Palaeozoic ◽  
New Perspective ◽  
Reservoir Potential

The Georgina Basin formed as a shallow intracratonic depression on the Australian craton along with a number of other basins in the Proterozoic and early Palaeozoic, probably in response to the break up of the Proterozoic supercontinent. Since all of these basins evolved under similar tectonic and sea-level controls, the basins all have similar sediment successions and, it might thus be assumed, similar petroleum prospectivity. One basin, the Amadeus Basin, currently has petroleum production, suggesting a potential for exploration success in the other intracratonic basins.In the Amadeus Basin the main petroleum prospects lie within or adjacent to major sub-basins that formed along the Basin's northern margin. The Georgina Basin has sub-basins that formed along its southern margin, almost as a mirror image of the Amadeus Basin. The lower Palaeozoic section of the Toko Syncline in the southern Georgina Basin has hydrocarbon shows in Middle Cambrian to Middle Ordovician rocks. Source rocks appear to have developed within the transgressive systems tract and the condensed interval of the highstand systems tract, at times when the basin was starved for clastic sediments and carbonate production was restricted.Seismic data acquired in the 1988 survey are of a higher quality than that previously obtained in the area. Its interpretation portrays the westward thrusting French Fault at the eastern edge of the Toko Syncline with potential hangingwall and footwall traps. Cambro- Ordovician Georgina Basin sediments subcrop the overlying Eromanga Basin with angularity, providing potentially large stratigraphic traps. Fracturing of the Cambrian and Ordovician carbonates within fault zones, and solution porosity at the unconformity, would also enhance reservoir potential in the area. Perhaps most significantly, the new data also shows an earlier, apparently independent basin completely buried beneath the Georgina section. The concealed section may simply be a very thick, early Upper Proterozoic section, or perhaps an equivalent to, or a lateral extension of the McArthur Basin. Recent work in the McArthur Basin has shown considerable source potential in the McArthur and Roper Groups, which may support the possibility of an additional, as yet unrecognised, source beneath the Georgina Basin.

Relative abundance of the central rock-rat, the desert mouse and the fat-tailed pseudantechinus at Ormiston Gorge in the West MacDonnell Ranges National Park, Northern Territory

2013 ◽  
Vol 35 (2) ◽  
pp. 144 ◽  
Author(s):  
G. P. Edwards
Keyword(s):  
Population Ecology ◽  
Relative Abundance ◽  
National Park ◽  
Northern Territory ◽  
Mammal Species ◽  
The West

This study examines the relative abundance of two species of sympatric rodent, the desert mouse (Pseudomys desertor) and the central rock-rat (Zyzomys pedunculatus), and a sympatric dasyurid (Pseudantechinus macdonnellensis) in relation to rainfall in the West Macdonnell Ranges National Park, Northern Territory, over a 6-year period. Seventeen trapping sessions were conducted between July 2000 and September 2006. All three species showed spikes in abundance during 2001 and 2002, which were very wet years, and then declined as rainfall diminished. Z. pedunculatus was not trapped at the sites beyond June 2002 while P. desertor was not trapped beyond September 2002. P. macdonnellensis was trapped in low numbers between September 2002 and February 2005 but was not trapped subsequently. Rainfall and the abundance of all three mammal species were clearly correlated. However, the patterns of abundance were subtly different. Z. pedunculatus exhibited three distinct peaks in abundance during the study (July 2000, April 2001 and March 2002), P. desertor exhibited two distinct peaks (July 2001 and June 2002) while. P. macdonnellensis exhibited only one peak in abundance (March 2002). The results of this study provide more evidence that populations of both arid Australian rodents and some dasyurids are influenced by rainfall. The study also provides some insights into the population ecology of the poorly known and threatened central rock-rat.

scholarly journals Art. XI.—Summary of the Geology of Southern India

1846 ◽  
Vol 8 (15) ◽  
pp. 213-270 ◽  
Author(s):  
Captain Newbold
Keyword(s):  
Short Distance ◽  
Detailed Account ◽  
Southern India ◽  
Western Boundary ◽  
The West ◽  
Geographical Position ◽  
The Village ◽  
Coromandel Coast

Geographical Position.—About nine miles inland of Pondicherry on the Coromandel coast, Lat. 11° 56′ N., are beds of limestone rising in gentle undulations, and running in a S.E. by E. direction, almost parallel with the coast, for a distance, as far as I was able to trace, of about four or fire miles. Of these strata no detailed account had been published up to the date of my visit in March, 1840. They are seen to crop out near the villages of Sydapett, Carassoo, Coolypett, and Vurdavoor, from a superincumbent tertiary lateritic grit imbedding large quantities of silicified wood, and of which a description has been given by Lieutenant Warren: who has, however, overlooked the fossil limestone. The beds of the latter dip very slightly easterly. The greater part of the surface of the limestone is concealed by the soil and vegetation. A short distance further towards the west it is again covered by beds of the silicified wood deposit, and both are underlaid by plutonic and hypogene rocks, which crop out near the village of Trivicary, and form the western boundary of the fossiliferous beds. Rolled and angular fragments of the hypogene rocks are scattered here and there over the limestone, as well as fragments from the silicified wood beds, and from the limestone itself; the surface of the latter has evidently been exposed by the denudation of the superincumbent beds. It appears in surface-worn tables traversed by innumerable fissures.

Excavations of Ermine Street in Lincolnshire

1959 ◽  
Vol 39 (1-2) ◽  
pp. 77-86 ◽  
Author(s):  
Charles Green ◽  
P. A. Rahtz
Keyword(s):  
Western Boundary ◽  
The South ◽  
The West ◽  
South Side ◽  
North West ◽  
Main Street ◽  
Trunk Road

The course of the Roman road from London to York, today known as Ermine Street, is well attested. Much of it underlies our comparable modern trunk road, the Great North Road (A1), but there are many deviations. To review the East Midland sector, the modern road covers approximately the Roman road from Huntingdon to the south-east gate of the walled town DVROBRIVAE at Water Newton. Here the modern road bears more to the west and leaves the Roman line. This passes through the ancient town as its main street, crosses the river Nene and continues in the same line until, at a point some three miles south-east of Stamford, it bears more westerly, running west-north-west through Burghley Park. It crosses the Great North Road on the western boundary of the park, where it was exposed in 1732 and seen by Stukeley (1883, ii, 269). From this point its course alters to north-west and, after crossing the river Welland, it underlies a suburban road in the western part of Stamford and crosses the Empingham (Oakham) road (A606). North of this it is seen as a boldly-upraised ridge crossing several fields diagonally until, some three-quarters of a mile south-east of Great Casterton, it joins once again the line of the Great North Road and runs parallel to and immediately adjoining the south side of the modern roadway.

scholarly journals Mean Conditions and Seasonality of the West Greenland Boundary Current System near Cape Farewell

2020 ◽  
Vol 50 (10) ◽  
pp. 2849-2871
Author(s):  
Astrid Pacini ◽  
Robert S. Pickart ◽  
Frank Bahr ◽  
Daniel J. Torres ◽  
Andrée L. Ramsey ◽  
...  
Keyword(s):  
Current System ◽  
Labrador Sea ◽  
Western Boundary ◽  
Coastal Current ◽  
Boundary Current ◽  
The West ◽  
West Greenland ◽  
Irminger Sea ◽  
West Greenland Current ◽  
Recirculation Gyre

AbstractThe structure, transport, and seasonal variability of the West Greenland boundary current system near Cape Farewell are investigated using a high-resolution mooring array deployed from 2014 to 2018. The boundary current system is comprised of three components: the West Greenland Coastal Current, which advects cold and fresh Upper Polar Water (UPW); the West Greenland Current, which transports warm and salty Irminger Water (IW) along the upper slope and UPW at the surface; and the Deep Western Boundary Current, which advects dense overflow waters. Labrador Sea Water (LSW) is prevalent at the seaward side of the array within an offshore recirculation gyre and at the base of the West Greenland Current. The 4-yr mean transport of the full boundary current system is 31.1 ± 7.4 Sv (1 Sv ≡ 106 m3 s−1), with no clear seasonal signal. However, the individual water mass components exhibit seasonal cycles in hydrographic properties and transport. LSW penetrates the boundary current locally, through entrainment/mixing from the adjacent recirculation gyre, and also enters the current upstream in the Irminger Sea. IW is modified through air–sea interaction during winter along the length of its trajectory around the Irminger Sea, which converts some of the water to LSW. This, together with the seasonal increase in LSW entering the current, results in an anticorrelation in transport between these two water masses. The seasonality in UPW transport can be explained by remote wind forcing and subsequent adjustment via coastal trapped waves. Our results provide the first quantitatively robust observational description of the boundary current in the eastern Labrador Sea.

scholarly journals Conservation and change on Edinburgh's defences:archaeological investigation and building recording of the Flodden Wall, Grassmarket 1998-2001

2004 ◽  
Vol 10 ◽  
Author(s):  
John Lawson ◽  
David Reed ◽  
Colin Wallace ◽  
Jonathan Millar ◽  
Mike Middleton
Keyword(s):  
18Th Century ◽  
16Th Century ◽  
Western Boundary ◽  
Surrounding Area ◽  
The West ◽  
The North ◽  
Restoration Work ◽  
Ancient Monument ◽  
North Western ◽  
Southern Section

This report presents the results of a historic building survey and archaeological watching brief undertaken between 1998 and 2001 during restoration work (undertaken as part of the Scottish Dance Base development) on the Flodden Wall running between Edinburgh's Grassmarket and Johnston Terrace. The Flodden Wall is the name given to the 16th-century extension of the capital's town defences, traditionally seen as having been constructed in the months following the defeat at Flodden in 1513. Prior to this project the extent and condition of this particular stretch of the Flodden Wall (the north-western boundary of the Grassmarket and a Scheduled Ancient Monument) was not fully understood. This project has shown that here the Flodden Wall and surrounding area had undergone three major phases of construction and redevelopment, from its origins in the early 16th century to the formation of a drying green (Granny's Green) to the west of the Wall in the late 19th century. In particular the results have demonstrated that the surviving southern section of the Wall here was largely rebuilt during the third quarter of the 18th century, when a complex of buildings was constructed along Kings Stables Road abutting the Wall's western face.

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